Egg Content of Noodles by Quantitative Analysis of Characteristic Proteins of the Egg

A new method has been developed for determining the egg content of noodles. Extracts of noodles were prepared in 0.15M NaCl and fractionated by disk electrophoresis on polyacrylamide gel. In the electrophoretic patterns of extracts from noodles with different egg content, bands of proteins originating from eggs were found. The densitometric measurement of intensity of one of these bands (Mb = 0.21) permitted the quantitative evaluation of the egg content of noodles.

Potential emerging chemical risks in the food chain associated with substances registered under REACH

A screening procedure for the identification of potential emerging chemical risks in the food and feed chain developed in a previous EFSA-sponsored pilot study was applied to 15021 substances registered under the REACH Regulation at the time of evaluation. Eligible substances were selected from this dataset by excluding (a) intermediates handled under strictly controlled conditions, (b) substances lacking crucial input data and (c) compounds considered to be outside the applicability domain of the models used. Selection of eligible substances resulted in a considerable reduction to 2336 substances. These substances were assessed and scored for environmental release (tonnage and use information from REACH registration dossiers), biodegradation (predictions from BIOWIN models 3, 5 and 6 evaluated in a battery approach), bioaccumulation in food/feed (ACC-HUMANsteady modelling) and chronic human health hazards (classification according to the CLP Regulation for carcinogenicity, mutagenicity, reproductive toxicity and repeated dose toxicity as well as IARC classification for carcinogenicity). Prioritisation based on the scores assigned and additional data curation steps identified 212 substances that are considered potential emerging risks in the food chain. Overall, 53% of these substances were prioritised due to chronic hazards identified in REACH registrations dossiers only (i.e. hazards not identified in classifications from other sources). Bioaccumulation in food and feed predicted on the basis of ACC-HUMANsteady modelling identified many substances that are not considered bioaccumulative in aquatic or terrestrial organisms based on screening criteria of the relevant ECHA guidance documents. Furthermore, 52% of the priority substances have not yet been assessed for their presence in food/feed by EU regulatory agencies. This finding and illustrative examples suggest that the screening procedure identified substances that have the potential to be emerging chemical risks in the food chain. Future research should investigate whether they actually represent emerging chemical risks as defined in EFSA's mandate.

Development of a novel scoring system for identifying emerging chemical risks in the food chain

The European Food Safety Authority (EFSA) is responsible for risk assessment of all aspects of food safety, including the establishment of procedures aimed at the identification of emerging risks to food safety. Here, a scoring system was developed for identifying chemicals registered under the European REACH Regulation that could be of potential concern in the food chain using the following parameters: (i) environmental release based on maximum aggregated tonnages and environmental release categories; (ii) biodegradation in the environment; (iii) bioaccumulation and in vivo and in vitro toxicity. The screening approach was tested on 100 data-rich chemicals registered under the REACH Regulation at aggregated volumes of at least 1000 tonnes per annum. The results show that substance-specific data generated under the REACH Regulation can be used to identify potential emerging risks in the food chain. After application of the screening procedure, priority chemicals can be identified as potentially emerging risk chemicals through the integration of exposure, environmental fate and toxicity. The default approach is to generate a single total score for each substance using a predefined weighting scenario. However, it is also possible to use a pivot table approach to combine the individual scores in different ways that reflect user-defined priorities, which enables a very flexible, iterative definition of screening criteria. Possible applications of the approaches are discussed using illustrative examples. Either approach can then be followed by in-depth evaluation of priority substances to ensure the identification of substances that present a real emerging chemical risk in the food chain.

[Assessment of breast feeding rates during compulsory vaccination: preliminary outcomes]

AIM

In consideration of the World Health Organization (WHO) recommendations on promoting and supporting breast feeding, a measurement of breast feeding rates was planned within Vercelli's Province (ASL 11, Piedmont, Italy) in order to compare the local situation to the national and international one, and to promote ideas and strategies for increasing the practice of breast feeding up to six months or beyond.

METHODS

During Diptheria Tetanus whole cell Pertussis vaccination (DTP) vaccination a questionnaire about their children's feeding was handed out to all mothers. Preliminary outcomes were elaborated after a follow-up of six months.

RESULTS

So far 1591 questionnaires have been collected. During the first DTP immunizations 31.63% of the children were exclusively breastfed and 15.81% were partially breastfed. At the second vaccination, 11.14% and 37.68% of infants were completely and partially breastfed, respectively. A 36.11% of partially breast feeding still emerged during the third DTP vaccination.

CONCLUSIONS

The outcomes of this study are inferior compared to WHO expectation and to national statistics. Increasing breast feeding rates should consequently become a priority aim, pursuing it through the health workers training, the support of mothers who encounter difficulties during their hospital stay or at home, and making the public aware of breast feeding practices.

Structural specificities and significance for coeliac disease of wheat gliadin peptides able to agglutinate or to prevent agglutination of K562(S) cells

Two peptides corresponding to bread wheat A-gliadin fragments 31-43 and 44-55, well known for their ability to damage the coeliac disease intestinal mucosa both in vitro and in vivo, have been confirmed to be very active in inducing in vitro agglutination of K 562 (S) cells. Removal of six amino acid residues from the carboxy-terminal end of the 31-43 peptide, or of five amino acid residues from the amino terminal end of the 44-55 peptide, resulted in a lower, but still very significant, cell agglutination activity. The peptide consisting of ten amino acid residues with a molecular mass of 1157.5 Da, isolated from durum wheat gliadin, was able to prevent agglutination of K 562 (S) cells induced not only by prolamine peptic-tryptic digests from all the cereals toxic in coeliac disease (i.e. bread wheat, rye, barley and oats), but also by the 31-43 and 44-55 peptides. The ability to protect K 562 (S) cells from agglutination was exhibited to the fullest extent also by all the peptides derived from the 1157.5-Da peptide by five progressive deletions of the terminal carboxylic residue, whereas the sixth consecutive deletion yielded a completely inactive peptide. A similar total loss of activity was observed upon addition of a glycine residue to the amino terminal residue of the 1157.5-Da peptide and all the above-mentioned active peptides derived from it. The remarkable sequence homologies existing between peptides able to induce [Gln-Gln-Gln-Pro and -Pro-Ser-Gln-Gln-] or to prevent [H2N-Gln-Gln-Pro-Gln-Asp-COOH] induction of cell agglutination strongly suggest that all these peptides compete for identical or structurally related binding sites on the cell surface.

A small peptide from durum wheat gliadin prevents cell agglutination induced by prolamin-peptides toxic in coeliac disease

A peptide (m.w. 1157.5 Da) able to prevent the agglutination of K562(S) cells induced by the peptic-tryptic prolamine digests of the cereals toxic in coeliac disease (i.e. bread wheat, rye, barley and oat) was characterized as one of the components of the peptic-tryptic digest of durum wheat gliadin. This peptide was synthesized in a high degree of purity with the solid phase method with the Applied Biosystem 431A. An amino acid sequence was identified in the 1157.5 Da peptide as being related to the largest common sequences previously detected in a series of bread wheat toxic peptides by other authors.

Mannan and oligomers of N-acetylglucosamine protect intestinal mucosa of celiac patients with active disease from in vitro toxicity of gliadin peptides

Wheat flour and other cereals toxic for celiac patients contain an alcohol-soluble protein fraction that, under experimental conditions simulating in vivo protein digestion, yields peptides that agglutinate undifferentiated K 562(S) cells. In contrast, cereals well tolerated in celiac disease (i.e., rice and maize) do not. Furthermore, purified A-gliadin peptides that damage in vitro-cultured flat celiac mucosa are powerful agglutinins for K 562(S) cells, whereas A-gliadin peptides that do not show any adverse in vitro effect on celiac intestine lack agglutinating activity. Mannan, acetylglucosamine, and its oligomers (N,N'-diacetylchitobiose and N,N',N"-triacetylchitotriose) were able to prevent and reverse cell agglutination induced by peptides from all the toxic cereals. Moreover, mannan and N,N',N"-triacetylchitotriose exhibited a protective effect on intestinal mucosa specimens of patients with active celiac disease cultured with wheat protein-derived peptides. These data are consistent with the hypothesis that the agglutinating and toxic peptides are bound by carbohydrates.

A basis for estimation of consumption: literature values for selected food volatiles. Part III

Quantitative data on volatile compounds have been reported in 16 food items. No publications reporting quantitative data were found for two of these 16 food products, i.e. avocado and jackfruit. About 550 volatile compounds have been assayed globally in the other 14 food products. Mango and raspberry were the products with the greatest number of volatile compounds; the most representative substances were benzaldehyde, ethyl acetate, limonene, and 2-phenylethanol.

Intestinal mucosa of celiacs in remission is unable to abolish toxicity of gliadin peptides on in vitro developing fetal rat intestine and cultured atrophic celiac mucosa

Subfraction 2R of fraction 9 from a peptic-tryptic-pancreatic digest of wheat gliadin is known to be toxic in vivo to celiac patients. We have found that fractions 9 and 2R inhibit the in vitro development of fetal rat intestine and the increase of enterocyte height occurring in organ culture of atrophic celiac mucosa (0.1-0.5 mg/ml medium). Other peptide fractions of the gliadin digest are devoid of such in vitro effects. Subfraction 2R, after incubation with morphologically normal small intestinal mucosa of celiacs in remission and ultrafiltration, was still very active in both culture systems at low concentration (0.1 mg/ml); on the contrary, subfraction 2R was inactivated after incubation with normal mucosa. These results are compatible with the hypothesis that there is a mucosal defect in handling gliadin peptides in celiac disease, and suggest that there is either a primary (or secondary) enzyme deficiency or some other mechanism operating in the intestinal mucosa of celiac patients in remission.

Prevention by mannan and other sugars of in vitro damage of rat fetal small intestine induced by cereal prolamin peptides toxic for human celiac intestine

Peptic-tryptic-cotazym and peptic-tryptic digests were obtained, simulating in vivo protein digestion, from pure "bread" wheat gliadins and from rye, barley, and oats prolamine and tested on small intestine cultures from fetal rats. When tested at a concentration of 0.1 mg of peptides/ml of culture medium the peptic-tryptic-cotazym and peptic-tryptic digests of gliadin and prolamines were very active in slowing in vitro development of fetal rat intestine and in increasing the occurrence and severity of degenerative changes. The ability of some sugars to interfere with inhibition of fetal intestinal morphogenesis induced by these peptides was also tested. Mannan at a concentration of 0.1 mM was effective in allowing intestinal morphogenesis to take place in the presence of prolamine peptic-tryptic-cotazym and prolamine peptic-tryptic digests of the four toxic cereals. Some oligomers of N-acetyl-glucosamine were also effective in blocking the inhibitory effect of "bread" wheat gliadin peptides. These data are compatible with the hypothesis that some sugars may exert a protective effect on the toxic activity of cereal prolamin peptides on the human celiac intestine.

An analysis of cereals that react with serum antibodies in patients with coeliac disease

Sera from six children with active coeliac disease, and elevated titres against gliadins and from six age-matched controls, were examined for IgG antibodies against different cereal proteins by a solid-phase radioimmunoassay. Antibodies to the major wheat proteins and the prolamines of other cereals were present in low titre in all control sera. In coeliac sera, significantly higher titres were found against A-gliadin, as well as against hexaploid and tetraploid wheat whole gliadins. Gliadin peptic-tryptic digest retained a significant antigenic activity, completely lost by peptic-tryptic-pancreatic digest. High titres were also found when coeliac sera were tested against wheat glutenins, albumins, and globulins, as well as against barley, oats, and maize prolamines; rice prolamines gave lower titres. Serum from whole gliadins and A-gliadin immunized rabbits showed a similar spectrum of reactivity against prolamines as coeliac sera. Our results indicate a dissociation between immunogenic properties of cereal proteins and toxicity in coeliac disease.

A basis for estimation of consumption: literature values for selected food volatiles. Part II

In this paper we present a compilation of quantitative literature data on volatile compounds in 15 food items including some brandies, meats, oils as well as vegetables, vinegar and potatoes. Levels of the volatile compounds identified (approximately 900) in this group of food items are generally in the ppm range. Carboxylic acids were present in much higher levels in plum brandy, vinegar, lamb and mutton (heated), whereas alcohols, esters and carbonyls aldehydes are particularly abundant in brandy.

An assessment of the safety of tocopherols as food additives

This paper is a critical review of data relevant to the safety of tocopherols as food additives. Tocopherols are considered from the standpoint of their chemical-physical properties, occurrence in nature and use in commercial products. Dietary intake and kinetic and metabolic data, as well as biological activity and interactions with other vitamins, are also examined. The subjects discussed include acute, subchronic and chronic toxicity data, reproduction and teratogenesis studies, and observations in humans following high intakes of tocopherols. On the basis of the comprehensive experimental and clinical data available on alpha-tocopherol, the chemical and biological similarity of the alpha-, beta-, gamma- and delta-tocopherols and the information available on the levels of tocopherols used as food antioxidants, it is concluded that tocopherols are safe food additives.

A basis for estimation of consumption: literature values for selected food volatiles. Part I

This paper is a compilation of quantitative data available on volatile compounds reported so far in 18 food items including some legume, cereals, grapes and cheeses as well as crab, lobster, cocoa and chocolate. No publications reporting quantitative data were found for five of these 18 food products, i.e. sultana grape, broad beans, cassava, oat and rye. About 440 volatile compounds have been assayed globally in the other 13 food products and more than 50% of them were found in grape or in grape juice. Levels of these volatile compounds in the selected foods were generally in the ppb range and less often in the low ppm range. Very high levels were found for some carboxylic acids in cheeses and cocoa and for some alcohols and acids as well as for ethyl acetate in grape juice.

Biochemical, nutritional and toxicological aspects of alpha-amylase inhibitors from plant foods

This paper is a critical review of the available data on plant protein inhibitors active either on animal or endogenous plant alpha-amylases. The First Section is a review of available data on molecular properties of the purified inhibitors from cereals, legumes, colocasia and yam. The Second Section deals with properties of amylase-inhibitor complexes and parameters controlling the interaction between amylases and inhibitors. The Third Section discusses possible roles of these inhibitors in the plant, whereas Section Four focuses on nutritional and toxicological significance of amylase inhibitors for human beings and other mammals. Lastly Section Five examines some applications in medicine of alpha-amylase inhibitors from plants.

In vitro activation of adenylate cyclase of atrophic celiac intestinal mucosa by wheat gliadin-derived peptides

In order to demonstrate that gliadin peptides may interact with cell membranes of celiac small intestinal mucosa, the capacity of these peptides to activate the cell membrane enzyme adenylate cyclase was tested. The addition of peptides from bread wheat purified A-gliadin and whole gliadin (proteins that are toxic for celiac patients) enhanced the adenylate cyclase activity of crude cell membrane preparations obtained from atrophic small intestinal mucosa of celiac patients. No activation of adenylate cyclase of this tissue was observed with peptides from proteins nontoxic for celiac patients (bread wheat albumin and maize prolamin). Gliadin peptides did not activate adenylate cyclase of morphologically normal small intestinal mucosa from normal subjects or from celiac patients in remission. These results, therefore, suggest that peptides from bread wheat gliadin may interact with cell membrane of atrophic small intestinal mucosa of celiac patients.

Toxicity mechanisms of wheat and other cereals in celiac disease and related enteropathies

This paper is a critical appraisal of current theories on the mechanisms of toxicity of wheat and other cereals in celiac disease and some related enteropathies. The "peptidase deficiency," "primary immune defect," and "gluten-lectin" theories on celiac disease are examined and critically discussed on the basis of the relevant data available in 88 references. Special attention has been paid in this review to the nature of the cereal components triggering the appearance of toxic symptoms and signs in celiac disease as well as to underlying action mechanisms. The gluten-lectin theory is the one best able to explain, in addition to celiac disease, some secondary intolerances that may occur in temporarily predisposed individuals as a consequence of several causes, including viral hepatitis and intestinal infections, as well as the occurrence of intestinal lesions in healthy subjects administered very high amounts of gluten.

An in vitro animal model for the study of cereal components toxic in celiac disease

Peptic-tryptic-Cotazym (PTC) digests were obtained, simulating in vivo protein digestion, from rice, maize, rye, oats, barley, and sorghum prolamines and tested on small intestine cultures from rat fetus. The PTC digests of the prolamine fractions from rice and maize, even when tested at a concentration as high as 0.5 mg/ml, did not affect in vitro differentiation and maturation of fetal rat jejunum that took place in vitro in a way comparable to what happens in vivo. On the contrary, the PTC digests of prolamines from rye, oats, barley, and sorghum were very active in slowing down in vitro development of fetal rat intestine. These results further strengthen earlier findings and all together show that there is a strong correlation between toxicity results of cereal and/or cereal components assessed with clinical trials or in vitro systems based on bioptic specimens of intestinal mucosa from celiac patients and with the culture of rat fetal intestine. Therefore, the rat fetal intestine culture is considered to be an adequate model for screening and investigating cereal peptides which are toxic for the celiac small intestinal mucosa.

Agglutinating activity of gliadin-derived peptides from bread wheat: Implications for coeliac disease pathogenesis

The PT-digest of bread wheat gliadin was very active in agglutinating undifferentiated human K562(S) cells. This activity was quantitatively, but not qualitatively, similar to that of Con A or WGA. Moreover, Con A-induced cell agglutination was inhibited by mannan and mannose, WGA-induced agglutination by NAG only, and cell agglutination induced by bread wheat gliadin peptides was inhibited by each of these three saccharides. Not only was mannan the most active saccharide in preventing cell agglutination induced by bread wheat gliadin peptides, but it was also able to dissociate agglutinated cells. As compared to the PT- digest of whole bread wheat gliadin, the digest obtained from purified A-gliadin was tenfold more active. The PT-digest of durum wheat gliadin did not show any agglutinating activity.

In vitro proliferation of lymphocytes from celiac children and their first-degree relatives in response to wheat gliadin-derived peptides

Evidence is accumulating which indicates that immune reactions to gliadins are involved in the pathogenesis of celiac disease, as humoral- and cell-mediated immune responses to gliadins have been demonstrated in the jejunal mucosa and the peripheral blood of patients. An abnormal specific immunological response to gliadins is demonstrated not only in celiac children but also in their first-degree relatives. Seventy-eight percent of celiac patients, and 67, 87, and 100% of their fathers, siblings, and mothers, respectively, have a peripheral blood lymphocyte population reacting in vitro with a proliferation response to at least one of four peptide mixtures obtained from bread and durum wheat gliadins using a procedure simulating in vivo protein digestion. The specificity of this immunological hyperresponsiveness against wheat gliadins is shown by two sets of data: (a) Lymphocytes from celiac children and their relatives were much less sensitive to peptides from rice prolamin and not at all sensitive to peptides from wheat albumins. (b) Only 7% of 30 adult controls had a proliferative response of their peripheral lymphocytes to wheat gliadin peptides. It is not known at this time if healthy relatives of celiac patients mount an immune response against the intestine in vivo. However, it is possible that the presence of lymphocytes reactive to wheat gliadin peptides in apparently healthy relatives of celiac patients may explain why these relatives develop histologic evidence of celiac disease when their gluten intake is increased (Doherty M, Barry RF. Lancet 1981;1:517-20).

Effects of gliadin-derived peptides from bread and durum wheats on small intestine cultures from rat fetus and coeliac children

Peptic-tryptic-cotazym (PTC) digests were obtained, simulating in vivo protein digestion, from albumin, globulin, gliadin and glutenin preparations from hexaploid (bread) wheat as well as from diploid (monococcum) and tetraploid (durum) wheat gliadins. The digest from bread wheat gliadins reversibly inhibited in vitro development and morphogenesis of small intestine from 17-day-old rat fetuses, whereas all the other digests (obtained both from nongliadin fractions and from gliadins from other wheat species) were inactive. The PTC-digest from bread wheat gliadins was also able to prevent recovery of and to damage the in vitro cultured small intestinal mucosa from patients with active coeliac disease (gluten-induced entheropathy). The PTC-digest from durum wheat gliadins caused a much less adverse effect on this human pathologic tissue culture system.

Toxicology investigations with cell culture systems

This review concerns some of the cell culture systems that are most frequently used in toxicology investigations. In particular, it sets out to evaluate the effectiveness of these cell culture systems in assessing the toxic potential of chemicals. Metabolic studies and general and specific toxicology investigations are highlighted. Specific toxicology investigations relate to the effects of the tests substances on the highly specialized functions typical of the cell systems chosen. The general toxicology investigations include most of the other studies where differentiated or undifferentiated cells have been used to evaluate the effects of the tested substances on common basic biochemical processes essential for life. Lastly, we have attempted to focus attention on the most promising applications of cell cultures in toxicology studies for the near future and to identify those areas where further research is needed. Because of the several excellent reviews that already exist, we have decided not to consider cell cultures utilized in screening potential mutagens and carcinogens. We have also excluded investigations of drug therapeutic effects and action mechanisms of drugs.

Interaction of wheat monomeric and dimeric protein inhibitors with alpha-amylase from yellow mealworm (Tenebrio molitor L. larva)

The highly purified alpha-amylase from Tenebrio molitor L. larva (yellow mealworm) reversibly combines with two closely related homogeneous glycoprotein inhibitors, one dimeric (termed 'inhibitor 0.19') and one monomeric (termed 'inhibitor 0.28'), from wheat flour. As established by means of difference spectroscopy and kinetic studies, molar combining ratios for the amylase--inhibitor-0.19 and amylase-inhibitor-0.28 complexes were 1:1 and 1:2 respectively. Two amylase--inhibitor-0.19 complexes with slightly different retention volumes on Bio-Gel P-300 and only one amylase--inhibitor-0.28 complex were observed. Dissociation constants of the amylase--inhibitor-0.19 and amylase--inhibitor-0.28 complexes were 0.85 nM and 0.13 nM respectively. A strong tendency of both complexes to precipitate under an ultracentrifugal field was observed; the minimum molecular weight calculated for the two complexes under such conditions was approx. 95 000. The two complexes showed difference spectra indicating involvement of structurally related or identical tryptophyl side chains in the binding of inhibitors 0.28 and 0.19 to the amylase. A model summarizing the main features of the inhibition of the insect amylase by the two wheat protein inhibitors is proposed.

Toxicity of wheat flour proteins and protein-derived peptides for in vitro developing intestine from rat fetus

A peptic-tryptic-cotazym (PTC) digest of a crude wheat gliadin preparation was obtained under experimental conditions simulating in vivo protein digestion and then fractionated into 10 peaks by ion-exchange chromatography. PTC-gliadin digest and one of its subfractions (coded as fraction 9 according to its elution pattern) were very active in inhibiting in vitro development and morphogenesis of small intestine from 17- and 18-day-old rat fetuses, whereas they were harmless for the culture of jejunum from 21-day-old fetuses. PTC-digest also induced extensive tissue degeneration and necrosis of in vitro cultured small intestinal mucosa from patients with active celiac disease (gluten-induced entheropathy), but did not cause any detectable effect on histologically normal human small intestinal mucosa. Some wheat albumin and gliadin fractions were also tested on in vitro developing small intestine from 17-day-old rat fetus. Among all the tested protein fractions, only one gliadin fraction (coded as alpha 10-gliadin from its gel electrophoretic mobility) exhibited a toxic effect; morphologic alterations induced by alpha 10-gliadin were similar to those induced by PTC-digest and fraction 9.

Human health effects from accidental release of tetrachlorodibenzo-p-dioxin (TCDD) at Seveso, Italy

This paper is a progress report of the epidemiologic work carried out under the supervision of the Lombardy Regional Authority during the two years elapsed from the accident in a TCP-producing factory (ICMESA) in Meda (Italy), which resulted in the contamination of several towns of a large, densely populated area called the Brianza di Seveso with a total population of 220,000 inhabitants. A wide follow-up program is in progress in the Seveso area; it includes a clinical screening of the population living in the contaminated area and longitudinal and systematic health control of different groups at risk; a long-term morbidity cohort study has been also undertaken. TCDD exposure following the ICMESA accident resulted in an increased chloracne frequency. Neurologic examinations showed both signs of idiopathic subclinical neurologic damage and cases of clinically detectable idiopathic polyneuropathy in adults. A limited percentage of idiopathic hepatomegaly was reported to be present on clinical investigation; no information, however, is given on the criteria by which the hepatomegaly was investigated. Some alterations were observed in some exposed people in one or more liver tests (mainly transaminases and gamma-GT). So far, immunologic investigations, cytogenetic examination and embryomorphology analysis on cases of therapeutical or spontaneous abortions have not given abnormal results.

Structural studies of wheat monomeric and dimeric protein inhibitors of alpha-amylase

Two wheat monomeric protein inhibitors of alpha-amylase with mol.wt. 12000, designated inhibitors 0.28 and 0.39 according to their gel-electrophoretic mobilities, showed almost identical circular-dichroism spectra in both the far and near u.v. at different pH values as well as in the presence or absence of dissociating and reducing agents. Both inhibitors (0.28 and 0.39) were readily inactivated by reduction of the five disulphide bridges present in each inhibitor molecule. These properties are very similar to those exhibited by the wheat dimeric protein inhibitor of alpha-amylase with mol.wt. 24000, designated inhibitor 0.19 according to its gel-electrophoretic mobility. The N-terminal sequence of the 0.19 inhibitor was determined without separating its subunits and compared with that of the 0.28 inhibitor reported by Redman [(1976) Biochem. J. 155, 193--195]. Petide 'maps' from tryptic digests of reduced and carboxymethylated inhibitors 0.19 and 0.28 were compared. One molecule of reducing sugar is covalently bound per inhibitor-0.19 protomer and inhibitor-0.28 molecule. The results obtained strongly support previous findings indicating the structural equivalence of inhibitor 0.28 with each inhibitor-0.19 protomer and the common phylogenetic origin of these protein alpha-amylase inhibitors from wheat kernel.

Association of Tenebrio molitor L. alpha-amylase with two protein inhibitors--one monomeric, one dimeric--from wheat flour. Differential scanning calorimetric comparison of heat stabilities

Thermal stabilization resulting from protein . protein association between two protein inhibitors (coded as 0.19, a dimer, and 0.28, a monomer) from wheat flour and the alpha-amylase from Tenebrio molitor L. (yellow mealworm) larvae was investigated by differential scanning calorimetry (heating rate 10 degrees C/min). Thermograms (plots of heat flow vs. temperature) for the two inhibitors showed broad endothermic peaks with the same extrema (denaturation temperatures) at 93 degrees C, and equal, small enthalpies of denaturation (2 cal/g). The amylase produced a sharp endotherm at 70.5 degrees C, but a larger enthalpy change on denaturation (6 cal/g). The amylase . inhibitor complexes differed in thermal stability, but both showed significant stabilization relative to free enzyme. The complex formed with monomeric inhibitor 0.28 showed a higher denaturation temperature (85.0 degrees C) than that formed with dimeric inhibitor 0.19 (80.5 degrees C). This order of stabilization agrees with the relative affinities of the inhibitors for the amylase. These thermograms are consistent with previous results which indicated that 1 mol of amylase binds 1 mol of inhibitor 0.19.

Control through breeding methods of factors affecting nutritional quality of cereals and grain legumes

The comparison of nutritional quality parameters of proteins from cultivated cereal and legume species with animal proteins indicate the poor nutritional value of these plant products. The nutritive value of different cereal and legume species is very variable and large differences have also been observed coming from cultivars belonging to the same species. Many interpreting factors, such as protein content, essential amino acid composition and availability, protein digestibility and others are involved in such a highly variability. In addition, cereals as well as legumes may contain large amounts of antinutritional factors which can have serious effects under particular circumstances (e.e. tannins in a low-protein diet or phytates in a metal-deficient diet). Some legume species also contain chemicals of a different nature (i. e. lathyrogens, cyanogenetic glycosides, and others) which may be extremely toxic when ingested in significant amounts. The plant breeder attempting to develop higher-yielding, disease-resistant and nutritionally-improved crop varieties should be aware of such a complex of factors and alert to the possible production or increase of undesirable products or deleterious changes in chemical composition. Available data, although rather limited, indicate valuable breeding approaches to the improvement of nutritive value of cereal and legume grains for humans.

A model for the interaction of wheat monomeric and dimeric protein inhibitors with alpha-amylase

The amylase-protein amylase inhibitor system offers a unique model of specific and reversilbe protein-protein interaction. The monomeric and dimeric inhibitors, exhibiting closely related properties and interacting with the same amylase, also provide a convenient test to compare effects of monomer-monomer and monomer-dimer interactions between enzyme and inhibitor proteins.

Purification and properties of alpha-amylase from chicken (Gallus gallus L.) pancreas

Amylase from chicken pancreas was purified by an affinity method involving filtering a crude extract from pancreas through a Sepharose-wheat albumin column and eluting the retained enzyme with maltose. The purified amylase showed two active bands upon polyacrylamide electrophoresis in an alkaline buffer system and only one band in an acidic buffer system. The enzyme is a Ca2+-glycoprotein which behaves as a typical alpha-amylase. It consists of a single polypeptide chain with molecular weight 53,000 and contains 5.3 moles of reducing sugars per mole of protein. Optimal conditions of pH and temperature for the enzymic activity are 7.5 and 37 degrees C. The enzyme is irreversibly inactivated by removal of Ca2+ by exhaustive dialysis and is activated by the presence in the assay mixture of Cl-; other halides are less effective than Cl- in activating the enzyme.

Adaptation of the domestic chicken, Gallus domesticus, to continuous feeding of albumin amylase inhibitors from wheat flour as gastro-resistant microgranules

Albumin amylase inhibitors were extracted from wheat flour, precipitated by salting out the extract with ammonium sulphate, and enclosed in cellulose-coated microgranules resistant to the peptic action in the chicken gizzard. Continuous intake of gastro-resistant wheat albumins significantly (P less than 0.01) depressed chicken growth rate, whereas native wheat albumins did not show such an effect. After 4 weeks of treatment, treated chickens showed a growth rate identical to that of control chickens thus showing that an adaptation to the presence of wheat albumins in the diet had occurred. Treated chickens also showed pancreas hypertrophy and a number of histological changes in the pancreas indicating degenerative processes in progress. Moreover, in treated chickens the production of pancreatic amylase was markedly increased (P less than 0.02), whereas pancreatic protease activity was less affected. The data obtained suggest that the synthesis of pancreatic amylase in chicken is under some homeostatic control of alpha-amylase in the intestine.

The phylogenesis of protein α-amylase inhibitors from wheat seed and the speciation of polyploid wheats

Protein α-amylase inhibitors extracted with water from seeds of a number of Triticum and Aegilops species were characterized according to their molecular weights and action specificities towards human salivary and Tenebrio molitor L. α-amylases. Four inhibitor peaks, with molecular weights 60000, 44000, 22000 and 11000, active towards the two amylases have been detected. Another inhibitor peak with molecular weight 11000, only active towards the insect α-amylase, has been found in several species tested. Triticum urartu showed only the 22000 inhibitor peak, while other diploid Triticum species did not exhibit any inhibitory activity. All the diploid Aegilops species tested contained α-amylase inhibitors and the inhibitor patterns differed greatly even for closely related species. In general, tetraploid Triticum species (turgidun and timopheevi) exhibited amylase inhibitor patterns of higher complexity than diploid Triticum and Aegilops species.The relationships existing among the amylase inhibitor patterns of the Triticinae species tested are consistent with the hypothesis of the polyphyletic origin of tetraploid wheats by Sarkar and Stebbins (1956) and suggest that the amylase inhibitors from diploid species all derive from common ancestral genes.

Physical and catalytic properties of alpha-amylase from Tenebrio molitor L. larvae

The amylase from Tenebrio molitor L. larvae (yellow mealworm) was characterized according to a number of its molecular and catalytic properties. The insect amylase is a single polypeptide chain with mol.wt. 68000, an isoelectric point of 4.0 and a very low content of sulphur-containing amino acids. The enzyme is a Ca2+-protein and behaves as an alpha-amylase. Removal of Ca2+ by exhaustive dialysis against water causes the irreversible inactivation of the enzyme. Moreover, the enzyme is activated by the presence in the assay mixture of Cl-, or some other inorganic anions that are less effective than Cl-, and is inhibited by F-. Optimal conditions of pH and temperature for the enzymic activity are 5.8 and 37 degrees C. The insect amylase exhibits an identical kinetic behaviour toward starch, amylose and amylopectin; the enzyme hydrolyses glycogen with a higher affinity constant. Compared with the non-insect alpha-amylases described in the literature, Tenebrio molitor amylase has a lower affinity for starch.

Further characterization studies of the alpha-amylase protein inhibitor of gel electrophoretic mobility 0.19 from the wheat kernel

A highly purified amylase protein inhibitor from the kernels of hexaplois wheat, designated 0.19 according to its gel electrophoretic mobility, has been characterized according to its circular dichroism spectra determined at different pH values and in the presence or absence of dissociating and reducing agents. The 0.19 albumin has also been characterized according to the specificity with which it inhibits 21 alpha-amylases from different origins and according to its sensitivity to a number of chemical and enzymatic treatments of its inhibitory action on human saliva and Tenebrio molitor L. larval midgut alpha-amylases. Inhibitory activity of 0.19 toward human saliva amylase significantly increased when the inhibitor was incubated with the enzyme before the addition of starch, but it was not affected by the preincubation of 0.19 with starch. Maltose reversed the inhibition of human saliva by 0.19 and showed some inhibitory activity toward the enzyme. However, maltose concentrations that only slightly affected amylase activity were very effective in restoring the amylase activity inhibited by 0.19. The inhibitory action of 0.19 on human saliva and T. molitor L. amylases were equally resistant to trypsin and thermal treatments, but 0.19 was readily inactivated by incubation with pepsin or by reduction of disulfide bonds. The inhibition of the mammalian amylase by 0.19 was adversely affected by a treatment with CNBr (1:100 ratio of methionine residues to CNBr) whereas the inhibition of the insect amylase was not. As shown by circular dichroism measurements in the far ultraviolet, 0.19 is a protein with about 50% of ordered structure. Significant and largely reversible changes have been observed in the aromatic CD spectrum of 0.19 at alkaline pH values or in the presence of sodium dodecyl sulfate. These changes, which were associated with a partial loss of inhibitory activity, indicate that ionizable tyrosine groups contribute significantly to the ellipticity bands of 0.19 in the near ultraviolet.

Affinity column purification of amylases on protein inhibitors from wheat kernel

An affinity column was devised for the purification of a large number of amylases inhibited by the albumin from wheat kernel. The procedure involved linking the protein inhibitors from wheat to Sepharose and then specifically eluting the amylase adsorbed to the gel with a high concentration of maltose. By this procedure, the amylases from Tenebrio molitor L. (yellow mealworm) larvae and chicken pancreas were purified to homogeneity with good yields for the first time, as shown by both alkaline and acidic electrophoresis. Human saliva alpha-amylase, purified by the same procedure, showed specific activity and electrophoretic patterns similar to those obtained by other workers with different techniques.

Inhibition of amylases from different origins by albumins from the wheat kernel

The amylase activity of water extracts from 18 insect species, from 23 marine species and from 17 different species of birds and mammals was determined quantitatively. The inhibition of amylase in these extracts by three albumin fractions from the mature wheat kernel, which had been separated according to their molecular weights (60 000, 24 000 and 12 500 D), was determined as well. The inhibition activity of the three albumin fractions toward amylases extracted from a number of cereal species or from immature and germinating wheat kernel was also tested. The extracts from insects that are destructive of wheat grain and stored wheat products showed much higher amylase activities as compared to the other insect species that do not attack wheat and wheat products. On the basis of the effectiveness with which the three albumin fractions inhibit their activities, the amylase preparations tested were divided into susceptible, partially susceptible and resistent. Susceptible amylases, inhibited by any of the three albumin fractions, were found mainly in insects that attack wheat and in marine species. Partially susceptible amylases, inhibited by only one or two of the three albumin fractions, were present in a few avain and mammalian species including man. Resistent amylases were largely distributed in cereal, avian and mammalian species as well as in insect species that do not usually attack wheat grain or wheat flour products. At no stage of development, wheat alpha-amylase was inhibited by the albumin fractions from the mature kernel. The 12 500 dalton albumin fraction was the most effective in inhibiting insect amylases, but it was inactive toward avian and mammalian amylases. The 24 000 dalton albumin fraction was the most effective in inhibiting amylases from marine avian and mammalian species and inhibited as much as 33 amylases over 66 different amylases tested. It is suggested that protein inhibitors of amylase contributed to natural selection of polyploid wheats by giving some insect resistence to such wheats, even though some insect species were able to overcome this biochemical defense toa large degree by producing higher amylase activities.