Glutenin Proteins Research Articles

Glutenin proteins and gluten strength in durum wheat

An electrophoretic study of the glutenin proteins of durum wheat was undertaken using 102 breeding lines to investigate possible associations between these proteins and gluten strength. The low-molecular-weight glutenin polypeptides were found to be highly correlated with gluten strength. In contrast, the high-molecular-weight (HMW) glutenin polypeptides were found in general to be poor indicators of viscoelastic properties. However, the presence of the lowest-mobility HMW band appeared to have a positive effect on gluten strength. Breeding lines that contained gliadin band 42 and had intermediate dough strength instead of the dough weakness normally associated with this gliadin, were all found to contain this HMW glutenin polypeptide, which was not present in other lines examined.

Hexaploid wild emmer wheat derivatives grown under New Zealand conditions 1. Relationship between protein composition and quality parameters

Abstract Hexaploid derivatives of wild emmer wheat (Triticum dicoccoides Koern.) developed at the Volcani Research Center, Israel, were grown at Lincoln, New Zealand and tested for a number of milling and baking quality parameters and for gliadin and high molecular weight (HMW) glutenin protein composition. The average protein content of most of the derivatives was higher than that of the bread wheat standards (12.9 v. 11.4070) and about half showed an increase in loaf volume. Protein content, dough strength, and baking quality were related to the presence of specific protein components. In particular, superior quality was found to be closely associated with the presence of the HMW glutenin subunits 2*, 5 + 10, and 7 + 8. This agrees with results for European wheats.

Specificity characteristics of monoclonal antibodies to wheat grain storage proteins

A variety of monoclonal antibodies was prepared to wheat ( Triticum aestivum L.) gluten proteins, and their antigenic specificities were assessed using non-denaturing polyacrylamide gradient and SDS-polyacrylamide gel electrophoresis and immunoblotting techniques. While most anti-gliadin monoclonal antibodies bound to all gliadin protein bands separated by one-dimensional electrophoresis, several antibodies binding to small groups of gliadin proteins were identified. At high concentrations, these ‘specific’ antibodies bound to an increasing number of gliadins; this is likely due to the very high sequence homologies between groups of gliadin proteins. Several monoclonal antibodies with specificities for glutenin proteins were produced. These antibodies bound to all major glutenin subunits, although at low antibody concentrations some bound selectively to a single subunit. Other anti-glutenin antibodies bound to minor glutenin subunits and a variety of gliadin proteins. Several bound to gamma gliadins and high-molecular-weight glutenins, suggesting that these groups of proteins bear considerable homology. The results are reviewed in relation to known information on gluten protein structure, derived from DNA-sequencing studies.

Detection of quality differences among wheats by high-performance liquid chromatography

Proteins extracted with various solvents from small wheat flour samples were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC) and size-exclusion HPLC (SE-HPLC). RP-HPLC analysis of gliadin proteins can identify wheat varieties and, for durum wheats (used for pasta products), can rapidly determine quality. After lower-molecular-weight proteins are extracted, high-molecular-weight glutenin proteins can be reduced, alkylated, isolated and analyzed by RP- or SE-HPLC. The ratio of high- to low-molecular-weight glutenin subunits can be used to determine the quality of wheats used to make bread.

Fractionation of acetic acid-soluble proteins from wheat gluten by hydrophobic interaction chromatography: Evidence for different behaviour of gliadin and glutenin proteins

Acid-soluble proteins extracted from defatted gluten were fractionated by hydrophobic interaction chromatography on Phenyl-Sepharose CL-4B. The hydrophobicities of gliadin and glutenin components were compared directly on the basis of their respective adsorption properties. No difference was observed between the adsorption properties of the gliadin components of defatted gluten and those of the gliadin components of non-defatted or partially defatted glutens. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed that unreduced glutenin aggregates were present in several chromatographic fractions; this suggests that they differ with respect to their surface hydrophobocities as do the gliadin components. Some glutenin aggregates displayed hydrophobicities similar to those of gliadins but others were significantly more hydrophobic. Differences in subunit composition were observed among glutenin aggregates differing in surface hydrophobicity.

The effect of heat on wheat gluten and the involvement of sulphydryl-disulphide interchange reactions

The baking performance of gluten declined progressively on heating and most of its functionality was destroyed by 75°C. This was accompanied by a decreased extractability of the gluten proteins in an SDS buffer, and chromatographic examination of the SDS-extracted proteins showed that glutenin proteins were affected predominantly. Extractability of gliadin proteins in aqueous propan-l-ol was unaffected by heating at temperatures up to 75°C but decreased markedly after heating at 100°C. Electrophoresis showed that the gliadin patterns were essentially unaltered up to 75°C but at 100°C ω-gliadins dominated the patterns. Both the change in propanol extractability at 100°C and the alteration in the gliadin pattern were reversed by including dithioerythritol in the extradant. Total free sulphydryl groups were measured and these were esssentially constant irrespective of temperature. However, there was a progressive shift of free sulphydryl groups from an SDS-extractable to an SDS-insoluble form. Chromatographic examination showed that free sulphydryl groups were found predominantly in glutenin aggregates of lowest molecular weight and in gliadins; sulphydryl groups in these glutenin species were particularly involved in the changes occurring at 55–75°C. These data indicate that there are heat-induced alterations in gluten proteins at temperatures above 55°C, which appear to be involved in the loss of functionality (baking performance) on heating. It is postulated that the glutenin proteins are unfolded on heating up to 75°C and that this facilitates sulphydryl/disulphide interchange between exposed groups. The protein is then ‘locked’ into the denatured state on cooling due to this disulphide bond rearrangement. At temperatures above 75°C the gliadin proteins are also affected, involving similar mechanisms.

Detection by Gel Electrophoresis of Oligomers Formed by the Association of High-Molecular-Weight Glutenin Protein Subunits of Wheat Endosperm

Evidence is presented that the high-molecular-weight glutenin protein subunits of hexaploid wheat can form oligomers which are detectable by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The oligomers appear when trace amounts of 2-mercaptoethanol (2-ME) are used in the extracting solvent, although the presence of a small disulphide compound (cystamine di HC1) was found to enhance their resolution. These oligomers are not present when high levels of 2-ME are used, which indicates that disulphide bonds (probably inter-molecular) are essential to maintain the association of the constituent polypeptides. It was found that (i) the subunits show specificity when they associate to form oligomers, for some subunit associations were not detected amongst the oligomers (ii) the subunits controlled by chromosome ID are extensively involved in oligomer formation and (iii) different combinations of subunits controlled by chromosome IB apparently differ in their ability to associate with subunits controlled by other chromosomes. The role of the oligomers in the structure of native glutenin is discussed and their possible influence on bread-making quality considered.

Mapping of the Hor-3 locus encoding D hordein in Barley

The hordein storage proteins of barley (Hordeum vulgare L.) are of intense interest due to their genetic diversity and prominence and impact on the industrial and agricultural uses of the seed. Two major hordein loci have been previously mapped on chromosome 5 (Hor-1 and Hor-2 encoding the C and B hordeins, respectively). A third major locus, Hor-3, which codes for D hordein, has been located in the centromeric region of chromosome 5, probably on the long arm. Two allelic variants with apparent molecular weights of 83,000 and 91,000 and similar isoelectric points of 8.0 comprise the products of this locus in the barley varieties 'Advance' and 'Triple Awned Lemma'. The D hordein examined is similar in molecular weight and isoelectric point to the high molecular weight (HMW) glutenin proteins encoded by the 1B chromosome of wheat (Triticum aestivum L.).

Inheritance of glutenin protein subunits of wheat

The inheritance of the high-molecular-weight (HMW) glutenin protein subunits in hexaploid wheat has been investigated by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis to examine the segregation of these subunits in 496 test-cross seeds. The parents of the f1 hybrid were chosen so that the test-cross seeds segregated for all the HMW glutenin bands. Two glutenin subunits from one parent, believed to be controlled by genes on chromosome 1D, segregated as alternatives to two glutenin subunits from the other parent, a result that supports the assumption that these subunits are controlled by allelic genes at each of two loci that are very closely linked. Similar results were obtained for glutenin subunits believed to be controlled by chromosome IB, which suggests that these subunits are controlled also by allelic genes at each of two loci that are very closely linked. A single glutenin subunit band, believed to be controlled by chromosome 1A, segregated as an alternative to a single glutenin band from the other parent, except that one seed did not possess either band. It was concluded that these bands are controlled either by allelic genes or by nonallelic genes that are very closely linked.

Effects of an Agropyron chromosome on endosperm proteins in common wheat Triticum aestivum L.).

An Agropyron chromosome having a gene conferring blue color on the aleurone layer of the kernel endosperm causes a 15% increase in total grain protein content when it is added to the common wheat (2n=42) complement. In contrast, there is no effect of this chromosome on total protein content if it replaced part of a wheat chromosome. Endosperm protein components of isolines having blue aleurone due to the Agropyron chromosomes being added (2n=44) or translocated (2n=42) were compared to normal nonblue isoline counterparts. Gliadin proteins separated by aluminum lactate (pH 3.2) polyacrylamide gel electrophoresis (PAGE) in one or two dimensions showed greater staining intensity for the blue addition isolines (2n=44) than nonblue (2n=42) isolines. However the 42-chromosome blue isoline did not show increased protein staining over the nonblue isoline, but at least five protein differences were detected between the lines. SDS-PAGE showed that blue and nonblue differences were expressed primarily in the gliadins, but also in the glutenin, globulin, and albumin proteins.

Variation in Glutenin Protein Subunits of Wheat

The high molecular weight glutenin protein subunits (those with apparent molecular weight in the range 80000 to 140000) of 98 wheat cultivars have been examined using a discontinuous gel-electrophoresis system. The number of bands present in each cultivar ranged from three to five and at least 34 different band patterns were observed. Examination of these patterns revealed that some bands, or band combinations, are mutually exclusive and that they can be assigned to three groups. In one group, two pairs of bands occur as alternatives and these bands are controlled by genes on chromosome 1D of wheat. In the second group, three possibilities occur with cultivars possessing either one of two single bands or neither band. These patterns are controlled by a gene or genes on chromosome 1A. In the third group nine patterns occur, four consisting of single bands and five consisting of a pair of bands. Four of these nine patterns have been shown to be controlled by genes on chromosome 1B. The variation detected in the glutenin subunits is useful for cultivar identification, has a bearing on our understanding of wheat evolution, and raises questions concerning the nature of this variation.

Subunit composition of wheat glutenin proteins, isolated by gel filtration in a dissociating medium

Proteins were extracted from wheat meal or flour in 0.1 M acetic acid, 3 M urea and 0.01 M CTAB and fractionated in columns of cross-linked Sepharose in the same solvent. An heterogeneous fraction of high molecular weight eluted from the column which, when reduced and subjected to SDS-polyacrylamide-gel electrophoresis, separated into 12 components. Their molecular weights ranged from about 31,500 to 136,000. The unreduced protein was insoluble in salt solutions and aqueous ethanol but soluble in 0.1 M acetic acid and was therefore defined as glutenin. Glutenins of different molecular weight were made up from the same subunits but in different proportions. The ethanol-soluble proteins (gliadins) of the flour were fractionated in Sephadex G-100. The protein component that was excluded from the Sephadex gel, often described as high-molecular-weight gliadin, was shown to contain 8 distinguishable subunits and they had identical mobilities to 8 of the 12 subunits of glutenin.

Wheat flour proteins: the selectivity of solvents and the stability of gliadin and glutenin fractions of stored flours.

AbstractA gel‐filtration study of extraction of wheat proteins by eight separate solvent systems is presented and the nature of the protein classes extracted by each solvent has been quantified. As judged by carboxymethylcellulose ion‐exchange chromatography, gel‐filtration and starch‐gel electrophoresis, no storage changes have occurred in wheat flour gliadin and glutenin proteins extracted from flours kept at 25, 12 and ‐20 °C for 18 months. SDS‐polyacrylamide‐gel electrophoresis shows minimal change in the gluten molecular weight distribution on storage. Six and twenty‐year‐old flours were also tested.

STATISTICAL EVALUATION OF TECHNIQUES FOR PREDICTING BAKING QUALITY OF WHEAT CULTIVARS

Simple correlations between a number of quality parameters, their heritabilities and an evaluation of the best combination of these parameters to predict loaf volume, were determined from data for 26 cultivars of spring wheat grown at four locations in Western Canada. Highly significant correlations between remix loaf volume and each of Zeleny sedimentation value, farinograph dough development time, farinograph mixing tolerance index, proportion of residue protein, and glutenin protein were obtained. Sedimentation value, 1000 kernel weight, mixing tolerance index, flour yield, farinograph absorption, and remix loaf volume all had high heritabilities over the four locations. Using the simple correlations as a guide, regression formulae yielding the best predictions of remix loaf volume were developed. Residue protein content, Zeleny sedimentation value, and farinograph dough development time provided the most useful information for predicting baking quality by a single test.

EFFECT OF THE D GENOME ON THE PROTEIN OF THREE CULTIVARS OF HARD RED SPRING WHEAT

The protein compositions of the AABB tetraploid wheats derived from three common wheat (Triticum aestivum L. em Thell.) cultivars, Prelude, Rescue and Thatcher, were compared with those of their hexaploid counterparts. Quantitative distribution of the soluble protein fractions showed that all wheats contained similar quantities of albumins and globulins. Tetraploids of Rescue and Thatcher contained more gliadin, more glutenin and less insoluble residue protein than the corresponding hexaploids. In contrast, the tetraploid of Prelude contained similar amounts of gliadin, glutenin and insoluble protein residue as its hexaploid. Amino acid compositions of the flour and the solubility fractions for all wheats examined were essentially the same. Electrophoretic patterns of the proteins in the four soluble fractions showed that significant qualitative differences existed among the cultivars studied. The patterns for each extracted tetraploid and its hexaploid counterpart were essentially the same.