Isolation of three hordeins

Three major barley prolamins of high, and nearly equal, electrophoretic mobilities have been separated and analysed. They appear to be free from SH groups and to have single polypeptide chains. The amino acid composition is broadly similar to those of wheat gliadins but the barley proteins have more Pro, Lys, Gly and Val, and less Asx. The molecular weights of the fast, middle, and slow members of the group are 43, 44 and 43 × 10³, respectively. The relative mobilities stem from the presence of an extra Arg residue in the two faster proteins, while the dissimilar speeds within this pair are accounted for by inequality of molecular size.     

Cereal proteins: Immunological studies

A rabbit antiserum to Wichita gliadin has been used to study cereal proteins by the double diffusion technique. Wheat flours give strong reactions, at least five antigens being common to the eight varieties tested, but the number may exceed nine. Rye flour shows a closely similar antigenic reaction to that of wheat, but barley appears to contain only three wheat antigens, two of these being in trace quantities. Oat and maize do not react to any significant extent. Gliadins of four wheats reveal at least six confluent lines, and the glutenins produce four, which give reactions of identity with gliadins. Fractionation of glutenin on Sephadex, however, indicates that only the minor, soluble, part of glutenin, containing traces of gliadins and components of low electrophoretic mobility, is responsible for the main glutenin reaction. The bulk of the glutenin is insoluble and so not amenable to double diffusion techniques, but nevertheless evidence has been produced that this material may contain one or more polypeptide chains which have certain antigenic (and therefore structural) features in common with one, or possibly two, gliadin proteins.     

Purothionin analogues from barley flour

Acid treatment of a light-petroleum extract of barley flour yielded two proteins (termed hordothionins) closely similar in electrophoretic behaviour to the purqthionin doublet obtained from wheat by the same procedure. The major (faster) component, hordothionin a has been obtained apparently pure. Comparison of its amino acid composition, peptide maps, immunological reactions and C-terminal end group with those of purothionin a has confirmed the relationship between the proteins from the two genera although some differences in amino acid composition and sequence have been found. Extraction of barley flour with buffered saline followed by acid treatment yielded proteins with similar properties to the hordothionins; this supports previous observations on the relationship between the purothionins and their corresponding globulins.     

Comparative physico-chemical studies on purified trypsin inhibitors from the endosperm of barley, rye, and wheat

The dominant trypsin inhibitors of the endosperm of barley, rye and wheat were investigated in a series of comparative studies. The barley and rye inhibitors showed a reaction of partial immunochemical identity, whereas no immunological cross-reactions between the wheat inhibitor and the inhibitors from barley and rye were detected. The molecular weight of the barley inhibitor is about 14,500, and of the rye and wheat inhibitors about 12,000. The three inhibitors had very similar amino acid compositions, but the wheat inhibitor seemed to contain nine disulfide bridges whereas the barley and rye inhibitor contain five and four, respectively. This may explain the higher stability of the wheat inhibitor towards proteolytic inactivation by pepsin and chymotrypsin. All three inhibitors were very stable to temperatures at 100 degrees C. The barley inhibitor was much less active against porcine trypsin, and especially human trypsin, than against bovine trypsin, whereas the inhibition by the rye and wheat inhibitor was less dependent on the origin of the enzyme.     

Baking quality versus some biological activities of proteins extracted from the grain of wheat varieties harvested in 1986

Grain of six winter and spring wheat varieties differing in baking quality were included in the study. A number of technological analyses were performed. Albumins, globulins and gliadins were washed out. Location of inhibitory activities of alpha-amylases in extracted proteins against enzymes of various origin were tested and compared to baking quality of the wheat grain. Also, the location of endogenous amylase activity in extractable proteins was compared to baking quality of the studied varieties. A certain correlation between the incidence of higher inhibition activity against alpha-amylase of Sitophilus granarius L. and good baking quality has been found. However, location of endogenous alpha-amylases in grain seems to be a better criterion classifying varieties according to their baking quality. So-called baking varieties have higher and only activity of endogenous alpha-amylases located in albumin and gliadin fractions, whereas in poorest, “non-baking” varieties this activity is also located in the globulin fraction.     

Isolation of two γ-gliadins from cappelle-desprez

The strongest band in the electrophoretic pattern of Cappelle-Desprez gliadin owes its intensity to the coincidence of two proteins. These have been isolated and characterised. They have a fairly similar amino acid composition, typical of the gliadin class, and appear to be single polypeptide chains, free of SH groups and carbohydrate. Their molecular weights are 38 000 and 44 000. The higher mobility at pH 8.9 of the lighter molecule is attributed to its smaller size though the possibility also exists of its having fewer COO- groups. The equal mobility at acid pH arises because the extra resistance encountered by the larger molecule is balanced by a higher positive charge due to histidine. The proteins appear to correspond to the _γ2 and _γ3 Ponca gliadins isolated at Peoria, and this supports the idea that gliadins of equal mobility from different varieties have very similar structures. A rapid way of calculating recovered protein is mentioned.     

Comparison of wheat varieties by starch-gel electrophoresis of their grain proteins

Single extraction of wheat flour with water proved to be necessary for obtaining clear electropherograms of the albumin/globulin fraction; triple extraction was required to obtain a clear distinction of the gliadin components. As the ‘electrophoretic mobility’ does not have a constant value, a different characteristic, the R_v value, analogous to the R_t value in chromatography, is suggested as a measure of the relative mobility of the components, a characteristic which is not affected by experimental factors. From densitograms of gliadin fractions, 80 wheat varieties and selected lines from various parts of the world were arranged into five main groups, which formed a morphological series. Each main group comprised of a number of sub-groups which in certain cases were found to be based on genetic relationships. Densitograms of the albumin/globulin fractions could be used in conjunction with those of the gliadins for determination of wheat varieties.     

TEXTUROMETER AS A TOOL FOR STUDYING VARIETAL DIFFERENCES IN WHEAT FLOUR DOUGHS AND GLUTEN PROTEINS

The General Food's Texturometer has been used for studying the differences in wheat flour doughs prepared from 11 Indian wheat varieties of known gluten composition. The quantities of residue proteins in these varieties and the ratios of residue proteins over gliadins and glutenins were found to show high positive correlation with texturometer hardness and areas of first and second peaks. Adhesiveness was found to show high negative correlations. Of the gluten proteins only glutenins showed varietal differences i.e., the hardness and the areas of the first and the second peaks were found to increase from weak to strong varieties. The gliadins and the residue proteins of the varieties studied were found to be similar. Only gliadins were found to have adhesive character.     

Detection and quantification of adulteration of durum wheat flour by flour from common wheat using reverse phase HPLC

When common wheat (Triticum aestivum L) gliadins were separated by RP-HPLC, a major doublet peak eluted at 47.20 and 47.94 min. This peak was consistently found to be absent in Durum wheat (Triticum durum Desf) gliadins separated under identical conditions. In Durum wheat gliadins a characteristic small peak eluted at 48.30 min followed at 50.47, 510.37, 52.80 min by larger peaks. The peak area ratio of the peaks eluting at 50.47 and 51.37 min was found to be 2.18 (±0.14). This ratio was found to decrease proportionally on contamination of Durum wheat flour with flour from some common wheat varieties. This ratio alone was not enough to detect and quantify adulteration by all varieties of common wheat. An alternative method was found whereby the peak emerging between 47 and 49 min in the Durum wheat gliadin elution profile was expressed as a ratio of the total protein applied. This ratio was shown to increase when Durum wheat flour was adulterated with flour from common wheat thus enabling quantitative estimation of the level of adulteration. A third method of detecting adulteration of Durum wheat flour is also proposed in which the peak emerging between 47 and 49 min is collected and the protein separated by PAGE. The presence of more than one band of γ/β-gliadins is indicative of adulteration.     

Isolation of an albumin from Cappelle-Desprez and Manitou wheats

Small quantities of a wheat albumin have been isolated from two varieties, Cappelle-Desprez and Manitou. Both proteins have the same mobility on starch-gel electrophoresis in an acidic buffer. The molecular weights from gel electro-phoresis in sodium dodecyl sulphate agree within the limits of experimental error. Amino-acid analyses are close enough to suggest that the proteins have the same composition. A revised molecular weight of 13 000 is put forward for a previously isolated Cappelle-Desprez albumin,¹ the C-terminal amino acid of which has been shown to be valine.     

Puffing and Textural Characteristics of Chapati in Relation to Varietal Differences in Gluten Composition

Chapaties made from different wheat varieties differ in puffing and textural characteristics. These differences have been found to be related to the relative quantities of gliadins, glutenins and residue proteins in respective glutens. Wheat varieties having about equal quantities of gliadins, glutenins and residue proteins give fully puffed soft and pliable chapaties. Wheat varieties having more of residue protein give leathery chapaties and varieties having more of gliadin give relatively stiff chapaties. Applications of Warner-Bratzler shear press for evaluating chapati texture is discussed.     

Application of immunodiffusion in detecting the presence of barley in wheat flour

An immunological method for detection of barley contamination in wheat flour was developed. a rabbit antiserum to barley proteins was tested against different protein concentrations of barley and wheat extracts by the immunodiffusion technique. It was possible to identify with barley a typical precipitin band which is not present with wheat flour. the barley antiserum was then adsorbed by wheat and tested against wheat proteins contaminated with barley proteins at different concentrations. the results indicated that it is possible to detect a contamination of 5 % of barley proteins in wheat proteins. Samples of commercially available barley and wheat flour were also tested on agar plates against the barley anti-serum adsorbed from wheat. Again it was possible to detect a contamination of 5% of barley flour in wheat flour. It appears that this is a simple but specific immunological method suitable for routine testing.     

Hull-less Barley Varieties: Storage Proteins and Amino Acid Distribution in Relation to Nutritional Quality

Barley (Hordeum vulgare L.) has had an important impact on human nutrition. Hull-less barley is a genetically improved type that has been widely used in recent years. Six Brazilian hull-less barley varieties (IAC-IBON 214-82; IAC 8612-421; IAC 8501-31; IAC 8501-12; IAPAR 39-ACUMAI; IAC 8501-22) were analyzed for storage protein constituents, amino acid contents, and similarity among the hull-less barley varieties. Albumins, globulins, prolamins I and II, and glutelins were extracted and separated by SDS-PAGE. The total protein amino acid contents of the flour were also determined for each variety by TLC and HPLC. Variations in intensity and appearance and disappearance of protein bands were observed among the varieties suggesting genetic variability. However, the amino acid profile did not indicate any major variations in the amino acid concentrations. The high lysine and threonine total concentrations detected in the seeds of the hull-less barley varieties encouraged an investigation into the regulation of amino acid metabolism and storage protein synthesis.     

The varietal differences in some biological activities of proteins extracted from flours of wheat seeds harvested in 1986

Six wheat seeds varieties taken for experiments showed some differences in crude protein content ranging from 10.4-12.8%. A procedure for protein fractionation by the successive elimination of albumins, globulins and gliadins from the wheat varieties studied was elaborated. In the obtained protein fractions endogenous amylolytic and inhibitory activities tested against bovine pancreas trypsin and alpha-amylases of mammalian and insect origin were determined. The determined biological activities differ considerable among wheat varieties studied and were mainly located in albumins and gliadins while only a small amount were detected in globulins. Extractable proteins were relatively thermostabile and powerful inhibitors of the alpha-amylases examined. As the influence of environmental conditions was the same for all wheat varieties studied the observed differences in biological activities should be rather attributed to the genetic differences.     

Varietal differences in water-soluble gliadin fractions of Triticum aestivum and of Triticum durum Seeds

Water-soluble gliadin fractions from the endosperm of several varieties of Triticum aestivum and T. durum were analysed by disc-electrophoresis on polyacrylamide gel in a Tris-glycine buffer system. With this procedure, both anodic and cathodic bands were obtained. After aniline blue-black staining, the gliadin bands became coloured reddish-brown, whereas the albumin bands appeared blue-black. In spite of remarkable varietal differences, some characteristic gliadin-like bands can be used to differentiate bread from T. durum wheat. The biochemical connexion between gliadin-like fractions and gliadins is discussed.     

我国29种青稞的营养及功能组分分析

为了解我国不同青稞品种的营养及功能组分,对29种青稞的成分进行分析,包括碳水化合物、蛋白质、脂肪、氨基酸、灰分、水分及β-葡聚糖、总黄酮。研究结果表明:29种青稞中蛋白质含量变化范围为8.74%~13.16%,脂肪含量变化范围2.44%~4.48%,总氨基酸含量变化范围7.48%~11.86%,β-葡聚糖含量变化范围2.89%~6.11%,总黄酮含量变化范围0.11%~0.28%,灰分变化范围1.66%~2.95%,不同品种之间存在显著性差异;碳水合物和水分的变化范围分别为73.82%~78.30%和7.69%~9.68%,显著性差异不明显。29种青稞中均含有17种氨基酸,包括人体所需的8种必需氨基酸。其中,青稞XZDM00025的蛋白质、总氨基酸和总黄酮含量最高,青稞XZDM00027的β-葡聚糖含量最高,青稞XZDM00074脂肪含量最低。通过对比WHO/FAO理想蛋白质氨基酸模式,青稞的第1限制性氨基酸是甲硫氨酸,第2限制性氨基酸是赖氨酸,第3限制性氨基酸是异亮氨酸。采用聚类分析(组间连接-平方欧式距离)法将29种青稞分为7类,前4类都仅包括1个品种,第Ⅴ类包括6个品种,第Ⅵ类包括2个品种,第Ⅶ类包括17个品种,且各大类间营养和功能含量组分存在显著性差异。     

Hull-less Barley Varieties: Storage Proteins and Amino Acid Distribution in Relation to Nutritional Quality

Abstract

Barley (Hordeum vulgare L.) has had an important impact on human nutrition. Hull-less barley is a genetically improved type that has been widely used in recent years. Six Brazilian hull-less barley varieties (IAC-IBON 214-82; IAC 8612-421; IAC 8501-31; IAC 8501-12; IAPAR 39-ACUMAI; IAC 8501-22) were analyzed for storage protein constituents, amino acid contents, and similarity among the hull-less barley varieties. Albumins, globulins, prolamins I and II, and glutelins were extracted and separated by SDS-PAGE. The total protein amino acid contents of the flour were also determined for each variety by TLC and HPLC. Variations in intensity and appearance and disappearance of protein bands were observed among the varieties suggesting genetic variability. However, the amino acid profile did not indicate any major variations in the amino acid concentrations. The high lysine and threonine total concentrations detected in the seeds of the hull-less barley varieties encouraged an investigation into the regulation of amino acid metabolism and storage protein synthesis.     

Effect of malting on the protein and free amino nitrogen composition of sorghum

When sorghum is malted much of the nitrogen in the kernel is transferred to the roots and shoots. Examination of Osborne protein fractions extracted from the kernel reveals that as in the case of barley the prolamins are the major source of the nitrogen transferred. Electrophoretic prolamin bands remained unchanged during malting, indicating that prolamins are degraded directly to small peptides and amino acids. There was a general decline in the number of glutelin proteins whereas some albumin plus globulin proteins increased in quantity while others decreased. In the roots and shoots there was a considerable increase in both protein nitrogen and non-protein nitrogen as a result of the translocation of the products of storage protein breakdown from the kernel. Several-fold increases occurred in all of the nine essential amino acids determined. Quantitatively, the two most important free amino acids of sorghum malt appear to be asparagine and glutamine, as in germinated wheat and maize. This is in contrast to barley where proline is the major free amino acid.     

Partial characterisation of a wheat germ agglutinin and an albumin.

Using simple techniques, an agglutinin (WGA) and an albumin have been isolated from wheat germ in a sufficiently pure state for partial characterisation. WGA, which is a minor component (of the order of 0.01 %)of wheat germ, appears to be a protein with a mol. wt. of 17 800. It is not a glycoprotein and contains no SH groups. The amino acid analysis has been compared with those in the literature and the most probable composition has been estimated. It is exceptionally high in glycine and cystine. The protein exhibits microheterogeneity, resolving into three main bands on electrophoresis at acid pH. Small quantities of these components have been purified sufficiently for analysis. The small differences found in amino acid composition are in agreement with the observed mobility differences at acid pH. Examination by fingerprinting suggests that their sequences are close. There is some evidence that WGA associates at pH 8.5. The albumin has a mol. wt. of 13 000 and an amino acid composition typical of wheat endosperm albumins so far isolated. It has no SH groups or carbohydrate, and associates at pH 8.5. A single analysis was done on a coloured protein obtained as a by-product. Its polypeptide chain weight is 43 000.     

青稞品种对青稞发酵酒营养与感官品质的影响

本研究以7种西藏特有的青稞品种及相应发酵青稞酒为对象,基于理化性质、营养、风味和感官等指标,采用典范对应分析（canonical correspondence analysis,CCA）和主成分分析（principal component analysis,PCA）等探究青稞品种与其发酵酒品质的关系。研究表明,与青稞原粮相比,青稞酒体氨基酸中必需氨基酸占比增加,可能是酿造过程中非必需氨基酸转化形成了必需氨基酸。CCA结果显示不同品种青稞原粮在总氨基酸、γ-氨基丁酸、β-葡聚糖和总多酚含量等方面具有一定相似性,但其营养结构的差异经微生物生物化学转化得以放大,为筛选青稞酒的优质品种提供了可能。通过青稞原粮及相应青稞酒中的蛋白质、氨基酸、γ-氨基丁酸和总多酚水平等营养指标分析初步优选出‘藏青2000’为酿酒青稞品种,其次是‘隆子黑’‘芶芝黑’‘藏青25’。结合青稞酒营养、风味和感官等多维度指标,最终确定‘藏青2000’为最佳酿酒青稞品种,其次为各具特色风味的‘芶芝黑’‘隆子黑’‘藏青25’。本研究可为我国青稞酒领域的发展提供参考。