Relationship between wheat proteins

Booth, Michael R.; Ewart, J. A. D.

doi:10.1002/jsfa.2740210406

Cited by 20 publications

(3 citation statements)

References 17 publications

(1 reference statement)

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“…For the first time in a wheat flour, this procedure allowed us to identify, as tTG substrates in vitro, a few gliadin peptides having a specific amino acid composition amongst a myriad of other peptides. Contrary to what was expected, only a few gliadin peptides interacted with tTG even if a high content of Q residues was available along the gliadin chains [4,5]. Only one belonged to the Q‐X‐Q consensus sequence (peak 7, Table 1) while Q residues occupying the −2 position with respect to a P residue were preferentially modified, confirming previous data concerning tTG specificity [3].…”

Section: Discussionsupporting

confidence: 80%

“…In addition, because gliadin proteins are rich in Q and poor in K residues [4,5], in the absence of MDC, tTG may act as an acyl acceptor and form complexes with gliadin peptides. Assays to detect gliadin peptide–tTG complexes were unsuccessful owing to the high heterogeneity of the reaction mixture and the very high molecular weight of the protein–peptide complexes.…”

Section: Resultsmentioning

confidence: 99%

“…Gluten proteins and derived peptides are also good substrates for tTG‐catalyzed cross‐linking given the high frequency of Q residues, which account for about 40% [4,5]. In addition to forming gliadin–gliadin complexes, tTG can be incorporated into high molecular weight complexes with gliadins [6], giving rise to novel antigenic epitopes [2].…”

Section: Introductionmentioning

confidence: 99%

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Susceptibility to transglutaminase of gliadin peptides predicted by a mass spectrometry‐based assay

et al. 2004

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A peptidomics approach was developed to identify transglutaminase-susceptible Q residues within a pepsin^trypsin gliadin digest. Based on tagging with a monodansylcadaverine £uorescent probe, six K K/L L-, Q Q-gliadin, and low molecular weight glutenin peptides were identi¢ed by nanospray tandem mass spectrometry. In functioning as an acyl acceptor, tissue transglutaminase was able to form complexes with the glutamine-rich gliadin peptides, whereas by lowering pH, the peptides were deamidated by transglutaminase at the same Q residues, which were previously transamidated. The main common feature shared by the peptides was the consensus sequence Q-X-P. Our ¢ndings o¡er relevant information for the understanding of how dietary peptides interact with the host organism in celiac disease.

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Section: Discussionsupporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Susceptibility to transglutaminase of gliadin peptides predicted by a mass spectrometry‐based assay

et al. 2004

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A modified hypothesis for the structure and rheology of glutelins

Ewart¹

1972

J Sci Food Agric

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Cereal storage proteins, it is suggested, are more tolerant of genetic mutations than other proteins. Evolutionary tendencies may have been towards decreasing the cystine content and increasing the content of amino acids which are easily synthesised, especially those which are rich in nitrogen. The appearance of stress in molecular structure so that an intrachain SS bond is no longer able to close, thus creating interchain linkages, may have led to the origin of the glutelins.It is argued that a viscoelastic dough can be formed only if protein particles, which originate in the form of protein bodies, are able to form a continuous structure whether maintained by covalent bonds orland secondary forces. The constituent polypeptide chains of glutelins could be joined in a linear or a branched mode. A number of difficulties arise if the branched model is used to explain the properties of dough at the molecular level. In attempting to reconcile fact and theory, it is speculated that polypeptide chains of wheat, rye and barley glutelins form linear concatenations with two disulphide bonds connecting each chain to the next: continuity of structure in their doughs depends on entanglement and interaction by secondary forces. The glutelin molecules of oats and maize are unable to form a continuous network, hence the absence of viscoelasticity from doughs of these cereals. Two reasons are suggested: more probably the molecules are highly cross-linked in the branched mode and are thus incapable of significant entanglement; or if the molecules were cross-linked in the linear mode, poor solubility would ensure that protein-protein contacts in protein bodies were maintained, thus preventing dispersal of the protein and subsequent molecular entanglement. The glutelin molecules of sorghum appear to be too small to create a network by molecular entanglement. The importance of the disulphide interchange reaction is thought to lie in stress relaxation, but not in the creation of a dough structure. It is suggested that SS groups in viscoelastic doughs are sterically protected except when exposed by stress and consequently stress relaxation by SS interchange tends to occur only when it is needed.

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Sodium dodecyl sulphate electrophoresis of wheat gliadins

Ewart¹

1973

J Sci Food Agric

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Polypeptide chain weights of a-, 8-and y-gliadin fractions have been estimated by polyacrylamide gel electrophoresis in the presence of mercaptoethanol and sodium dodecyl sulphate. Values lie in the range 32 000 to 44 OOO. When available data on the amino acid analyses were adjusted and compared, significant similarities emerged. It is suggested that these gliadins contain a minimum of 4 cystine residues/molecule. The results provide support for the hypothesis that glutenins and gliadins have evolved from a common precursor. The results of an amino acid analysis of a previously unreported 8-gliadin component are included.

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Relationship between wheat proteins

Cited by 20 publications

References 17 publications

Susceptibility to transglutaminase of gliadin peptides predicted by a mass spectrometry‐based assay

Susceptibility to transglutaminase of gliadin peptides predicted by a mass spectrometry‐based assay

A modified hypothesis for the structure and rheology of glutelins

Sodium dodecyl sulphate electrophoresis of wheat gliadins

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