Chain Extension and Termination as a Function of Cysteine Content and the Length of the Central Repetitive Domain in Storage Proteins

• Published in: Journal of cereal science 2002-11, Vol.36 (3), p.313-325
• Main Authors: Tamás, László, Gras, Peter W., Solomon, Robert G., Morell, Matthew K., Appels, Rudi, Békés, Ferenc
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biotechnology; dough testing, gene manipulation, protein expression, size distribution, storage proteins, structure/function relationships, wheat quality; Food processing; Fundamental and applied biological sciences. Psychology; Genetic engineering; Genetic technics; Industrial applications and implications. Economical aspects; Methods. Procedures. Technologies; Miscellaneous; Synthetic digonucleotides and genes. Sequencing
• ISSN: 0733-5210; 1095-9963
• DOI: 10.1006/jcrs.2001.0457

Analogue glutenin proteins (ANGs) based on the barley seed storage protein C-hordein, modified to contain N- and/or C-terminal cysteine residues and varying lengths of repetitive domain, have been purified from a bacterial expression system. The proteins were used to modify the mixing, extension and baking properties of wheat flour doughs in small-scale tests. Comparison of the effects of simple addition of the proteins versus their chemical incorporation into the glutenin macropolymer has allowed us to assess the importance of cysteine content, cysteine position and repetitive domain length in determining dough mixing and processing properties. When incorporated, the proteins, along with small synthetic oligopeptides based on their N- and C-terminal sequences, change the amount of large glutenin polymers, and hence dough properties, in ways consistent with their action as either chain terminators (polypeptides with single cysteine residues) or chain extenders (polypeptides with two cysteine residues, one in either terminal domain). The gross effects of chain extension and termination may be further fine-tuned by modification of the molecular size of the incorporated proteins through alteration of their repetitive domains.