Zusammenfassung
Inhaltsangabe:Abstract:
1. High prevalence of antibodies to soy antigens was demonstrated not only in swine and poultry sera, but also in commercial products as horse-radish labelled antibodies from goats, commercial complement preparations manufactured from guinea pig sera.
2. Upon heat treatment, which is recommended for the inactivation of the anti-nutritive components of soybeans, the formation of protein fibrils may occur. This fibril formation is of amyloid character, which may render the proteins involved resistant to proteolytic digestion.
3. One or more of the components of the conglycinin preparation have chaperone activity, ie. prevents the aggregation of proteins, thus reducing digestibility.
4. A ccording to laser particle sizer test protein A containing Staphylococcus aureus cells show substantial size reduction if the protein A bound antibodies are exposed to the appropriate antigens. This size reduction may also be responsible for dermatological diseases if circulating antigens reach antibody covered bacteria in the skin and the resulting size reduction leads to local, heamatological dissemination of the disrupted bacterial colonies (atopic dermatitis).
5. Amylase and xylanase reduce the amount of antigens in soybean, thus demonstrating the antigenic role of polysaccharides and one of the possible pathways of enzyme supplementation benefits. The method used for this demonstration can also used for optimizing enzyme combinations for feeds of different composition.
6. Soy overfeeding may lead to kidney and pancreas conditions which are characteristic of the protein overdosing.
7. Circulating antibodies to soy or soy components themselves do bind complement thus compromising the non-specific immunity of the host.
8. Soy antigens and Clostridial antigens may have interactions and/or sequence homologies with immunopathological implications.
Inhaltsverzeichnis:Inhaltsverzeichnis:
Summary2
Aim of the study5
The use of soybean8
Soy proteins10
Food products containing soy components10
Pricing of soybeans11
Receipts in the food industry13
Major components of soybean meals14
Trypsin inhibitors14
Lipase inhibitor15
Soybean lectin15
Lipoxygenase16
Glycinin16
Beta-Conglycinin17
Soybean Hydrophobic Protein18
Soybean Hull Protein (Gly m 2)18
Soybean Profilin (Gly m 3)18
Soybean Vacuolar Protein (Gly m Bd 30k)18
Soybean allergen nomenclature18
Soybean allergy19
Levels of soybean allergens20
Soy lipids and […]
1. High prevalence of antibodies to soy antigens was demonstrated not only in swine and poultry sera, but also in commercial products as horse-radish labelled antibodies from goats, commercial complement preparations manufactured from guinea pig sera.
2. Upon heat treatment, which is recommended for the inactivation of the anti-nutritive components of soybeans, the formation of protein fibrils may occur. This fibril formation is of amyloid character, which may render the proteins involved resistant to proteolytic digestion.
3. One or more of the components of the conglycinin preparation have chaperone activity, ie. prevents the aggregation of proteins, thus reducing digestibility.
4. A ccording to laser particle sizer test protein A containing Staphylococcus aureus cells show substantial size reduction if the protein A bound antibodies are exposed to the appropriate antigens. This size reduction may also be responsible for dermatological diseases if circulating antigens reach antibody covered bacteria in the skin and the resulting size reduction leads to local, heamatological dissemination of the disrupted bacterial colonies (atopic dermatitis).
5. Amylase and xylanase reduce the amount of antigens in soybean, thus demonstrating the antigenic role of polysaccharides and one of the possible pathways of enzyme supplementation benefits. The method used for this demonstration can also used for optimizing enzyme combinations for feeds of different composition.
6. Soy overfeeding may lead to kidney and pancreas conditions which are characteristic of the protein overdosing.
7. Circulating antibodies to soy or soy components themselves do bind complement thus compromising the non-specific immunity of the host.
8. Soy antigens and Clostridial antigens may have interactions and/or sequence homologies with immunopathological implications.
Inhaltsverzeichnis:Inhaltsverzeichnis:
Summary2
Aim of the study5
The use of soybean8
Soy proteins10
Food products containing soy components10
Pricing of soybeans11
Receipts in the food industry13
Major components of soybean meals14
Trypsin inhibitors14
Lipase inhibitor15
Soybean lectin15
Lipoxygenase16
Glycinin16
Beta-Conglycinin17
Soybean Hydrophobic Protein18
Soybean Hull Protein (Gly m 2)18
Soybean Profilin (Gly m 3)18
Soybean Vacuolar Protein (Gly m Bd 30k)18
Soybean allergen nomenclature18
Soybean allergy19
Levels of soybean allergens20
Soy lipids and […]
Leseprobe
Inhaltsverzeichnis
ID 8363
Csàky, Istvàn: Soy Proteinosis
Hamburg: Diplomica GmbH, 2004
Zugl.: Szent István University, Dissertation / Doktorarbeit, 2004
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Die Informationen in diesem Werk wurden mit Sorgfalt erarbeitet. Dennoch können
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Diplomica GmbH
http://www.diplom.de, Hamburg 2004
Printed in Germany
Keywords: soy proteins, conglycinin, chaperone proteins, Clostridial antigens, soy
amyloid, guinea pig complement, feed amylase, feed xylanase, soy antigens,
Staphylococcus aureus, hyalin, soy proteinosis, cross reacting antigens, protein
digestibility, laser particle sizer
6XPPDU\
1. High prevalence of antibodies to soy antigens was demonstrated not only in
swine and poultry sera, but also in commercial products as horse-radish
labelled
antibodies
from
goats,
commercial
complement
preparations
manufactured from guine pig sera.
2. Upon heat treatment, which is recommended for the inactivation of the anti-
nutritive components of soybeans, the formation of protein fibrils may occur.
This fibril formation is of amyloid character, which may render the proteins
involved resistant to proteolytic digestion.
3. One or more of the components of the conglycinin preparation have
chaperone activity, ie. prevents the aggregation of proteins, thus reducing
digestibility.
4. According to laser particle sizer test protein A containing Staphylococcus
aureus cells show substantial size reduction if the protein A bound antibodies
are exposed to the appropriate antigens. This size reduction may also be
responsible for dermatological diseases if circulating antigens reach antibody
covered bacteria in the skin and the resulting size reduction leads to local,
heamatological dissemination of the disrupted bacterial colonies (atopic
dermatitis).
5. Amylase and xylanase reduce the amount of antigens in soybean, thus
demonstrating the antigenic role of polysaccharides and one of the possible
pathways of enzyme supplementation benefits. The method used for this
demonstration can also used for optimizing enzyme combinations for feeds of
different composition.
6. Soy overfeeding may lead to kidney and pancreas conditions which are
characteristic of the protein overdosing.
7. Circulating antibodies to soy or soy components themselves do bind
complement thus compromising the non-specific immunity of the host.
8. Soy antigens and Clostridial antigens may have interactions and/or sequence
homologies with immunopathological implications.
Contents
6XPPDU\
Aim of the study...5
The use of soybean...8
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Soybean is a key component of agriculture in the Northern hemisphere and is a major cash
crop in some countries of the Southern hemisphere. It is widely considered as "the only"
protein source in animal production. The overfishing leading to declining fish meal supply
and the problems of BSE related conditions leading to the ban on the use of animal protein
sources in feeding further increased the importance of soybean. Proprietory technological
progress and marketing efforts in recent years led to the introduction of several soybean
based products in the food industry. The application of genetic engineering methods in
developing soybean varieties led to the repositioning of soybean from a futures market
commodity traded in bulk to a technically sophisticated one, especially with the advent of
component pricing, in which soybean is to be priced according to the aggregated market
value of its components.
Although it was introduced to the US from the Far East at the beginning of the last century
as a crop for industrial lubricant production it became a panacea for the feed, food,
cosmetics and even construction industries. Its central role in determining feed and food
prices makes this crop a global spearhead for the praire-type agricultural production
systems.
Soybeans seems to be a double edged sword making labor saving and capital intensive
agriculture dependent on a single crop produced by a very limited number of producers. In
this role soybean has been subject to debates and success stories in the farming world and
in the medical community. Scores of scientists have studied the benefits and risks posed by
soybeans to human and animal health, each focusing on one component at a time. Each
text book of nutrition remarks that soybeans contain anti-nutrient components. Several
such components have been isolated, tested and described and all their harmful effects
listed separately. However, soybean seems to continue its glorious march into the heartland
of animal and human nutrition.
These developments, however, were not accompanied by similar developments in the
understanding of the biological and pathological importance of soybean components. Most
of the consumers consider soybean as a sole protein source which is efficiently digested
and can be conveniently used in compound feed manufacturing and in food industry. In
contrast to these developments feed and food quality testing lagged behind and even today
relies on simple chemical determinations which do not reflect biological values and
properties. The key index for soybean quality is nitrogen content detemined by Kjedahl
method or KOH solubility of proteins. The "fiber" content is also determined according to
other feeds regardless of the differences in fiber chemical composition. Among the anti-
nutritive compounds of soybean trypsin inhibitor determinations are used on the basis of a
method developed almost 80 years ago (Kakeda). The changes of the product during
processing is usually, but not frequently, monitored by the simple urease test. This test is
claimed to indicate insufficient heat processing, but fails to indicate inaquate processing.
Taking all these basic facts together, it was the aim of the present study to look into the
details of possible soybean feeding related problems. To this end properties of soybean
component proteins and interactions with bacteria, histological changes in soy fed animals,
anti-soy antibodies, the effect of enzymes on soybean proteins were studied with the aim to
find key elements of biological quality of soybean component proteins, keeping in mind
that all these effects may occur simultaneously in soy fed animals.
6
The study reviews soybean production, data on soybean components, covers soybean
related pathological conditions, outlines a general pathological model and recommends
testing methods for improving soybean based feed quality determination.
In the present study we define the
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interaction as a complex system. In complex systems each component is supposed to
interact with all others. In this sense the system definintion includes
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interaction as several bacterial species are present in the digestive tract and the skin. A step
further we also have to consider that soybean is not only a source of a variety of nutrients
utilized by the animal, but also a source of antigens including proteins, glycoproteins and
perhaps glycolipids. In this sense soybean components, including anti-nutritive factors, are
also antigens. In this respect the system can be described as
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Extending the animal components to diogestion and immune system leads to
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complex system.
In addition some biochemical properties of isolated soy protein complexes were studied
and a general pathological model described on the basis of published data and the results of
the present study. On the above assumptions a pathological model, described as the
flowchart, was studied.
7
1. Figure The flow chart of interactions between soy components, bacteria and host immunity.
8
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Soybeans have been cultivated in China for almost 5000 years, and the dietary use of soy
foods is well documented. Because of their exceptional protein content (35-38%), ease of
production, and long-term storage characteristics, soybeans have been highly prized as a
food source. The dietary use of soybeans is also widespread in Korea, Japan, and other
Asian countries. It is estimated that nearly 10% of the Japanese population's protein intake
is from soy foods. The per capita annual consumption of soybeans was 7.4 kg in Japan,
9.1 kg in South Korea, and 10.5 kg in Indonesia in 1994. Traditional soy foods include soy
in both fermented (eg. miso, shoyu and tempeh) and unfermented (eg. tofu and soymilk)
forms.
27%
15%
10%
5%
4%
4%
3%
3%
27%
0%
5%
10%
15%
20%
25%
30%
Pal
m
oi
l
R
ape
see
d
Sun
flow
er
Pe
anu
t
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ot
ton
se
ed
Co
co
nu
t
Pal
m
ker
ne
l
O
liv
e
S
oyb
ea
n
2. Figure Distribution of global vegetable oil production (2001)
45%
21%
15%
9%
3%
2%
5%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
US
A
Br
az
il
A
rg
enti
na
Ch
in
a
In
di
a
P
ar
agu
ay
Oth
er
3. Figure Distribution of global soybean production (2001)
9
67%
12%
6%
6%
4%
3%
2%
1%
0%
10%
20%
30%
40%
50%
60%
70%
80%
Soy
beans
R
apes
eed
C
ot
tons
eed
Su
n
flow
er
Fi
sh
Pea
nut
C
op
ra
Pa
lm
ke
rn
el
. Figure Distribution of global vegetable meal production (2001)
56%
12%
11%
10%
7%
2%
2%
0%
10%
20%
30%
40%
50%
60%
S
oy
be
ans
Ra
pes
eed
C
ott
ons
ee
d
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nu
t
Sun
flo
we
r
Co
pr
a
Pal
m
ker
nel
. Figure Distribution of global oil seed production (2001)
It is interesting that more than half of the global oil seed production is soybean, its share in
vegetable oil production is only 1/3 and in meal production it has a 2/3 ratio.
10
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As a protein source, soybean proteins are relatively high in lysine but low in methionine
and are therefore best combined with other protein sources to achieve nutritionally
balanced complementary protein supply. Soybeans also contain protease inhibitors,
which have demonstrated anticarcinogenic, anti-nutritional, and pancreas-enlarging effects
in animals. Besides animal feeds soybean is increasingly being used by the food industry.
The wide range of food products shows how frequently an average human consumer is
exposed to genuin or modified soy proteins and carbohydrates.
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Baby foods
Bakery goods
Black pudding
Bread (esp. high-
protein bread)
Breakfast cereals
(some)
Burger patties
Butter substitutes
Cakes
Candy
Canned meat or fish
in sauces
Canned or packaged
soups
Canned tuna
Chinese food
Muesli
Chocolates (cream centers)
Cookies
Cooking oils
Crackers
Desserts
Gravy (sauce) powders
Hamburger patties
Hot dogs
Hydrolyzed vegetable protein
(may be wheat)
Ice cream
Infant formula (including cow's
milk formula)
Liquid meal replacers
Margarine
Meat products (e.g., sausages,
pastes. Vienna sausages [wieners])
TV dinners
Pies (meat or other)
Powdered meal replacers
Salad dressings
Sauces (e.g.. Worcestershire,
sweet and sour, HP,Teriyaki)
Shortenings
Snack bars
Soups
Soy pasta products
Soy sauce
Soy sprouts (Chinese
restaurants)
Soybeans
Stock cubes (bouillon cubes)
Tofu
Cheese (artificial) made from
soybeans
1. Table List of soybean containing human foods
In order to manufacture such wide range of products different ingredients have to be
manufactured starting from the same or modified raw materials. In order to change the raw
material, genetic engineering is being used to modify the composition of soybeans. The
following traits are under "development", and their commercial introduction is underway.
High methionine
High lysine
Low allergens
Low galactical
Low raffinose
Low stachyose
Low phytate
Low trypsin inhibitor
High palmitic acids
High stearic/Low linoleic acid
Reduced goitrogens
High oleic acid
Low saturated fat
Null lipoxygenase
High sucrose
2. Table Different soybean traits under genetic modification to improve market value
11
The modified varieties are expected to result in improved consumer acceptance, gelation,
physical appearance, extended shelf-life, volume extension, higher water holding capacity,
etc.
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Soybean as a stock market commodity has a constantly changing price. However, this price
is determined by factors beyond textbook understanding of pricing. The emerging
genetically engineered soybean varieties called for a new pricing and cost calculation
method. The method is the Estimated Processed Value (EPV) which expresses the end
product contribution of the seed' components, mainly protein and oil. The total seed yield
serves as basis for calculating total value. This calculation bears special importance when
one considers the wide range of efforts to modify seed component composition. This US
calculation is balanced by the European appoach which considers genetically engineered
varieties as hazardous substances. If a variety is used for the production of a given
substance (eg. high oleic acid) the rest of the product is considered as hazardous waste. In
contrast, soy industry puts forward the notion of functional equivalence, claiming that in
GMO varieties all other components are equal. This is not always the case, as with high
protein varieties, even produced with recurrent selection, oil content is lower and oil
composition is changed. Processing technologies also modify the content of soy based
products. The next chart shows the major processing steps.
12
6. Figure Flow chart of major soybean processing steps
AND/OR
Cleaning, cacking,
dehulling, conditioning,
flaking
SOYBEAN HARVESTED
Wet
milling
Whole seed
cooking
Oil extraction
FMCG
and industrial
products:
fatty acids,
lecithin,
glycerol,
sterols, food
conditioners
Edible
soybean oil,
food
products
Feed
products
Solids:
feed
Soymilk,
juice
Coagulation:
tofu, curd,
food
products
Defatted soy
flakes
Solvent
extraction
Defatted
soyflakes, food
Toasting
Soybean meal: feed
Soy flour
Extrusion:
Textured
soyflour
Protein and
carbohydrate
extraction and
separation:
Soy isolate
Granulation:
Structured
soy isolate
Extraction
Traditional soy
concentrate
MW modification:
Functional soy
concentrate
Antinutritional factor
inactivation
Low antigen soy concentrate
Extraction: soluble
carbohydrate
13
The different products obtained by processing are used in the food industry. Just for the sake of
illustration a few receipts from the food industry.
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Cooking sausage: Supro 500E 0,5 kg/ 20 kg finished product
Smoked cooking sausage: skin emulsion: 10 kg/100 kg finished product
Blood sausage: 10 kg skin emulsion/100 kg finished product
Liver sausage: 12 kg skin emulsion/100 kg finished product
Cooking sausage: 2 kg soyprotein in 100 kg finished production
(Supro 500E is a soy protein isolate, skin emulsion is a 1:1 blend of soy concentrate and
deep frozen pig skin)
None of these soy additives have officially tested and declared biological quality
requirements and its in not known how different soy components maintain or lose their
functional properties during soy processing and food manufaturing.
14
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(excluding oils)
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The water extract of soybean inhibits trypsin activity. Osborn and Mendel (1917) were the
first to describe that raw soybean feeding depressed the growth of rats. The components
responsible for the inhibitor were isolated by Kunitz (1945) and Bowman (1946)
(Bowman-Birk inhibitor). The inhibitors belongs to the serpine family of inhibitors (serine
preotease inhibitors).
Out of the two types of inhibitors the Kunitz inhibitor is considered to be heat-labile, while
the Bowmna-Birk inhibitor is heat stable. DePietro and Liener (1989) concluded that both
inhibitors are sensitive to moist heat treatment, but despite their inactivation the soybean
meal retains some residual trypsin inhibitory activity (Anderson-Haferman et al., 1992).
Herkelman et al. (1992) demonstrated that low trypsin inhibitor soy varieties still needed
heat treatment to improve nutritional value. However, in inactivating trypsin inhibitors heat
treatment is critical, as overheating may lead to growth depression, as well. Overheating
leads to interaction between protein and reducing carbohydrates (see later). The reaction is
known as Maillard reaction which leads to growth depression in poultry (Clandinin et al.
1947).
Han, Parson and Hymowitz (1991) used chicks to compare protein digestibility in feeding
low trypsin inhibitor (SBTI: 5,6 mg/g), conventional (SBTI: 19,4 mg/g) and hull-free
soybean (SBTI: 2,9 mg/kg). It was found that even low SBTI soy was inferior to hull-free
soy, which indicates that hull may contain components affecting digestibility.
Kunitz inhibitor has a molecular mass of 20-25 kDa, the Bowman-Birk inhibitor is 6-10
kDa. Protease inhibitors differing from the Kunitz inhibitor differ in their acetone, etilene,
ammonium-sulphate solubility. The Bowman inhibitor is insoluble in acetone and inhibits
not only trypsin but chymotrypsin. Its inhibitory activity is resistant to heat, acid, alkali,
pepsin and papain treatment. Rackis and Anderson (1964) isolated three other inhibitors
(SBTI-A1, SBTI-B1, SBTI-B2). Yamamoto and Ikenaka (1967) separated another
inhibitor, what they called ,,1,9 S inhibitor. At the same time Frattali and Steiner (1968)
isolated three fractions from the Kunitz inhibitor which showed trypsin inhibiting activity.
It was assumed to represent genetic variants.
Frokiaer et al. (1998) demonstrated that purified pea and soybean Kunitz inhibitor reduced
protein digestibility in rats and in vitro, as well. According to Weder et al. (1998) Kunitz
inhibitor binds to human and bovine typsin in 1,4 mol/mol ratio. Bowman inhibitor binds
in 2 mol/mol ratio to the same enzymes. At pH 6.5 the Kunitz inhibitor forms a very tight
complex with trypsin from as wide source of enzyme as cow, pig, turkey, salmon, shark,
bovine and human trypsin.
Wan et al. (2002) fed dogs with Bowman-Birk inhibitor and detected the antigen in the
serum of animals in a dose dependent manner. However, serum anti-soy antibody levels
showed no correlation with serum antigen levels. The orally ingested inhibitor was
absorbed both in humans and dogs. Inhibition of trypsin activity in itself is not causing
digestive problems, but its action on exocrine pacreas leads to higher enzyme production in
rats and chicks. McLoad et al.(1972) describe similar pancreatic changes in soy and egg
15
trypsin inhibitor fed rats.
In rats and chicks fed soya protein or trypsin inhibitors hyperactive pancreas develops and
intestinal contents contain greater amounts of pancreatic enzymes. This way depression of
growth is not due to blocking proteolysis, but to pancreas hyperactivity. Soybean trypsin
inhibitor blocks trypsin to pancreas feedback mechanism so pancreas goes into hyper-
production of pancreatic enzymes causing rapid depletion/loss of essential nutrients.
In 86% of the soy allergic patients
IgE type antibodies reacting with Kunitz trypsin
inhibitor was detected (Baur et al. 1996). It seems that this inhibitor plays not only a role
in protein digestion, pancreas enlargement, but in immunological processes.
Protease inhibitors are used to treat clinical conditions eg. HIV infection. In HIV treatment
trials it was observed that protease inhibitors may lead to diarrhea and allergic reactions.
The redistribution of body fat was also observed including loss of fat from the face and
limbs and increase in abdominal fat. In a similar manner diabetes is also provoked by
synthetic protease inhibitors (
http://www.iapac.org/
).
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Nori and Matsushita (1974) isolated a less known lipase inhibitor from soybean seed which
inhibited swine pancreas lipase, but not amylase or ribonuclease. Its function and effect on
animals is not known. Satouchi et al. (1998) isolated a soybean lipoxygenase type lipase
inhibitor. The authors also observed pancreatic lipase inhibitor activity in lipoxygenase
which was distinct from lipoxygenase activity.
6R\EHDQ OHFWLQ
Lectins are carbohydrate specific proteins which occur both in plant s and animals. The
major characteristic is their ability to agglutinate erythrocytes by binding to specific
carbohydrate moieties.
In rats Green (1994) and
Grant et al. (2000) have demostrated that lectins trigger
prolonged release of cholecystokinin from I cells in the gut. The net effect of lectin or
proteinase inhibitors is to induce long-term hypersecretion of pancreatic digestive enzymes
and to cause enlargement of the pancreas by hypertrophy and hyperplasia. In addition,
dietary lectins induce the sustained release of a number of gastrointestinal hormones (Grant
et al. 1999), including secretin, enteroglucagon. Dietary kidney bean lectin interferes with
insulin synthesis in vivo (Bardocz et al., 1996). Dietary lectin is absorbed in intact form
and may act directly on pancreatic cells (Grant et al., 1999).
Soybean lectin is extensively endocytosed by intestinal epithelial cells. Benjamin et al.
(1997) demonstrated that soybean lectin injected into different cavities of rats induced a
typical inflammatory response characterized by dose-dependent exudation and neutrophil
migration within 4 h after injection. The co-injection of N-acetyl-galactosamine or
mannose, but not glucose or fucose, inhibited these effects, indicating that sugar binding
site is responsible for the inflammatory effect.
The effect of lectins on instestinal microflora was described by Banwell et al (1988) who
observed intestinal bacterial overgrowth in phytohaemagglutinin fed rats. Pusztai et al.
16
(1993) observed intestinal E. coli overgrowth in kidney bean lectin fed rats and similar
effect was described for soybean lectin. Ryder et al. (1994) observed with peanut lectin
that it stimulated the growth of colon explants from patients with colon polyps.
Douglas et al. (1999) observed improved metabolisable energy values in lectin-free
soybeans in poultry, however, the improvement failed to reach the level of properly
processed soybean meal, which indicates that lectins do not play a determining role in the
anti-nutritional effects observed with soymeals. Friedman et al. (1991) also emphasized the
importance of proper heat treatment in reducing anti-nutritive effects and made the same
observation with a Kunitz inhibitor free soybean variety as was done by Douglas et al. The
growth reducing effect was only partially associated with the presence or absence of
Kunitz inhibitors.
In rats Jordinson et al. (1997) observed appetite reducing release of cholecystokinin by
feeding lectins, including soybean lectin. Takashi et al. (2003) decribe appetite reduction in
beta-conglycinin gavaged rats with a simultaneous increase of plasma cholecystokinin
levels. Grant et al. (2000) observed that soybean but not kidney bean cause pancreas
growth in rats following prolonged feeding.
/LSR[\JHQDVH
The strong legume taste of soybeans limits its commercial utility due to the rancy flavor.
The lipoxygenase content is associated with the oxydation of polyunsaturated fatty acids
(Rackis et al., 1979). In soybeans, more than 50% of fatty acids are linoleic and linolenic
acids which are broken down by lipoxygenase to short chain aldehydes causing off-flavor.
Lipoxygenase makes up 1% of the seed proteins. Lipoxygenase is present in allelic form in
the seed and genetic engineering can be used to reduce the level of this enzyme present in
the seed (Nielsen, 1990).
*O\FLQLQ
Glycinin (320-360 kDa) belongs to the group of 11 S soy globulins belonging to the
legumin group of proteins. It is found in cotyledons of seeds in organelles called protein
bodies. Gylcinin is a hexamer of subunits 58-62 kD, each. The subunits originate from
homologous genes, their mature glycinin molecule consists of two peptide chains, both of
which originate from the same precursor molecule
that is cleaved post- or co-
translationally. The two chains of the mature subunit are coupled by a single disuphide
bond. One chain has acidic isoelectric point (31-45 kD), the other has basic one (18-20 kD)
(Nielsen, 1984). There are five subunits: A1aB1b, A2B1a, A1bB2, A3B4 and A5A4B3.
The subunits form trimers, mature proteins form hexamers, but these may also form
dodecamer complex of 12 subunits. This transition is reversible and pH and ionic strenght
dependent. The A1a subunit has a hydrophobic residue which binds bile acids (Choi et al,
2002). In humans 90% of the soy sensitive patients' sera contain antibodies to glycinin
(
http://www.food-allergens.de/symposium-vol1(2)/data/soy/soy-data.htm#Sensitization
)
When isolated 11S proteins are heated to 80C, a portion of the protein precipitates.
Examination of the precipitate shows that it consists almost exclusively of basic subunits.
The acidic subunits remain soluble after this heat treatment. When whole soybean protein
is given a similar heat treatment, no precipitation occurs. The addition of isolated 7S
globulin (mainly ß-conglycinin) to the 11S fraction will prevent the precipitation of the
17
basic subunits.
Marsman et al. (1997) studied the effect of different proteolytic enzymes on glycinin and
ß.conglycinin and found that extruded products show better digestibility than toasted or
untreated ones. In their SDS-PAGE studies the basic polipeptide chain of glycinin was the
most resistant to proteolytic digestion.
%HWDRQJO\FLQLQ
This group of soy proteins is sometimes referred to as 7 S globulins or vicilins as major
seed storage proteins in legumes. (In early separation efforts using ultracentrifuge other
proteins, like lipoxygenase, haemagglutinin contaminated the 7 S fraction.) ß-conglycinin
makes up 80% of the 7 S fraction.
According to Gibbs et al. (1989) vicilins evolved from a single ancestral gene through
unequal crossing and gene duplication. Beta-conglycinin (140-180 kDa) consists of 3
subunits: alpha (76 kDa, I=4,9), alpha' (72 kDa I=5,18), beta (53 kDa, I=5,66-6,0). The
subunits undergo post-translational glycosilation. The alpha and alpha' subunits contain 4
mol mannose, 12 mol Glcn and beta subunit 6 mol mannose and 2 mol GlcN. All the three
subunits form trimers of different combinations including eg. (alpha, alpha' and beta),
(alpha, beta, alpha') etc..
The ß-conglycinin shows termal transition at 70-75 °C and forms aggregates. Following
proteolysis by trypsin and chymotrypsin both glycinin and ß-conglycinin form large
intermedaites of approx. 280,000 kDa in which the basic subunits remain intact. According
to Perez et al. (2000) such enzyme modified intermediates are formed during digestion.
This resistence to thermal inactivation explains the thermal stability of the allergens. As
Mills et al. (2002) noted the poor solubility of these proteins and their intermediates may
be responsible for the relatively low level detection rate of related allergies. Although there
is no cross reaction in the allerginicity of alpha and beta subunits, all the three subunits
may provoke IgE production in allegic patients.
According to Lalles and Toulec (1996) in the solvent extracted soy products glycinin and
ß-conglycinin form 40% of proteins of allergic properties calculated on nitrogen basis. In
calves Lalles et al. (1996) observed that etanol-water extraction follwed by enzymatic
treatment decreased the allergen levels considerably.
Another physiological effect of ß-conglycinin was described by Nishi et al. (2003) who
observed that in rat small intestinal mucosal cells it increased cholecystokinin uptake. This
effect was reproduced by synthetic beta subunit fragment of 51-63 amono acid at as low as
3
µmol/L concentration. The effect could be abolished by cholecystokinin antagonist. In
animals the intraduodenal infusion suppressed feed intake. In another study Takashi et al.
(2003) also observed that ß-conglycinin peptone infusion strongly suppressed gastric
emptying with marked increases in portal CCK levels. This effect was absent if whole
soybean peptone was infused duodenally. The suppression of food intake by ß-conglycinin
peptone was abolished by an intravenous injection of devazepide, a selective peripheral
CCK receptor antagonist.
Maruyama et al. (2003) observed that the alpha' subunit of ß-conglycinin show a strong
phygocytosis stimulating activity which could be increased by the replacement of the N-
terminal threonine for phenylalanin or tryptophane leading to substantially higher
18
phagocytosis stimulating activity.
Another feature of ß-conglycinin is the upregulation of low density lipoprotein receptor,
which is the basis of product claims for reducing cholesterol levels (Sirtori et al., 1995).
According to Manzoni et al. (1998) this effect is triggered by the
' subunit and mutants
lacking this subunit fail to elicit the same response. Gianazza et al. (2003) studying food
industrial soy protein concentrates observed that Cholsoy and Croksoy products show
choletesrol reducing effects. These products contain mainly breakdown products of 7S
globulins and intact 11S globulins.
6R\EHDQ +\GURSKRELF 3URWHLQ
The allergen is a seed strorage protein with molecular mass of 7,5 kDa, isoelectric point
6,8. In the medical literature the allegen is referred to as Gly m 1.0101 and Gy m 1.0102. It
contains 4 disulphide bonds and carbohydrates, presumably as result of post-translational
modification. In humans this is the allergen with the largest incidence. The protein was
described by Odani et al. (1987).
6R\EHDQ +XOO 3URWHLQ *O\ P
The protein has molecular mass of 8 kDa with isolelectric point of 6,0. The N terminal
fragment of the allergen shows 60% homology with pea (Pisum sativum) disease response
protein (Codina et al. 1997).
6R\EHDQ 3URILOLQ *O\ P
The molecule has a molecular mass of 14 kDa and its characterics is binding to actin, a
cytoskeleton protein (Rih et al., 1999).
6R\EHDQ 9DFXRODU 3URWHLQ *O\ P %G N
It is found in the seed protein storgae vacules in the cotyledons. The molecule is
glycosilated and contains Man, GlNAc, Fuc and Xyl in a 3:3:1:1 molar ratio. The subunits
form aggregates up to a molecular mass of 3,000 kDa from the 34 kDa monomers. In the
plant it functions as serine protease. It shares 30% identity with house dust mite allergen. It
also binds to alpha and alpha' conglycinin monomers. It has 5 IgE binding epitopes (Helm
et al., 1998). According to Babiker et al. (1998) this molecule is responsible for the
Maillard reaction (see later), but this reaction eliminates its allergic potential. According to
Ogaewa et al. (1995) this allergen is identical with the oil-body associated protein of
soybeans.
6R\EHDQ DOOHUJHQ QRPHQFODWXUH
Common name
Identity
Gly m Bd 60K
alpha subunit of ß-conglycinin
Gly m Bd 30K (Gly m 1)
soybean oil-body-associated glycoprotein (vacuolar protein)
(34,000) (homologous to Der p 1 a house dust mite allergen,
19
Common name
Identity
Gly m Bd 60K
alpha subunit of ß-conglycinin
papain superfamily)
Gly m Bd 28K
vicilin-like glycoprotein (26,000)
Lectin
Cl. tetani toxin C fragment homology
Kunitz trypsin inhibitor
Cl.tetani toxin C fragment homology
Lipoxygenase-1
chain A + chain B
Clostridium perfringens (avian) alpha-toxin homology
Gly m 1.0101, Gly m 1.0102
Soybean hydrophobic protein, pea allergen homolgy
Gly m 2
Soybean hull protein
Gly m 3
Soybean profilin
3. Table Soybean allergens and their relationship to other proteins of medical importance
6R\EHDQ DOOHUJ\
Epidemic asthma occurs in areas where soybeans are unloaded. Epidemic outbreaks were
reported from Barcelona (Sunyer et al. 1989), Valencia, (Ballester, F. et al. 1999) and New
Orleans (White et al., 1997). Major allergens were found in the hull of the bean, but several
allergic molecules in the range of 5-17 kD have been detected (Codina et al., 1997, Baur et
al., 1996). In the study of soybean allergens considerable cross reactivity was found with
other legumes (Crawford et al., 1965). The clinical responses are serious when persons
allergic to peas, lentils, peanuts, kidney beans consume soybean containing products
(Moroz and Young, 1980). The 70 kDa alpha subunit of ß-conglycinin was shown to be
recognized by 25% of soybean sensitive patients with atopic dermatitis (Ogawa et al.
1995). Sevaral peanut allergens have been shown to cross react with soy allergens. No data
are available on the allergen potential of these antigens in animals.
During harvest, storage and processing temperature elevations may reach as high as 75 C
level, which leads to antigen structure changes. The IgG4 and IgE fractions of patients with
soy allergy show smaller activity against fresh soy hull antigens than to stored ones.
According to Codina et al. (1998) in soy hull heated to 80 C the protein antigens with
higher than 20 kDa disappear and new antigens (15,1 kDa and 10 kDa) appear, which can
not be detected in fresh hulls. It was found that in soy hulls an 8 kDa antigen is present
which shows a direct relationship to the severity of asthma. This allergen shows 71%
homology to the pea (Pisum sativum) ,,disase response protein. Codina et al (1997) found
that IgG4 shows stronger binding to this small antigen than IgE, which means that IgG4
antibodies may amplify asthma pathogenesis. In animal feeds soy hull is added to adjust
protein levels of the meal (Church,D.C. 1975). In human foods Herian et al. (1993)
observed several allergens by using human sera from allergic patients in RAST test.
In bakers with soy allergy Baur et al. (1996) detected the presence of IgE antibodies to
trypsin inhibitor and lipoxygenase. Sandiford et al. (1995) observed a common antigen of
Details
- Seiten
- Erscheinungsform
- Originalausgabe
- Erscheinungsjahr
- 2004
- ISBN (eBook)
- 9783832483630
- ISBN (Paperback)
- 9783838683638
- DOI
- 10.3239/9783832483630
- Dateigröße
- 3.1 MB
- Sprache
- Englisch
- Institution / Hochschule
- Szent István University – School of Veterinary Medicine
- Erscheinungsdatum
- 2004 (Oktober)
- Schlagworte
- chaperone amyloid clostridial antigens feed enzyme staphlococcus aureus
- Produktsicherheit
- Diplom.de
