Cereal Chem 62:405-412 | VIEW
The Beta-Turn Conformation in Wheat Gluten Proteins: Relationship to Gluten Elasticity.
A. S. Tatham, B. J. Miflin, and P. R. Shewry. Copyright 1985 by the American Association of Cereal Chemists, Inc.
A combination of circular dichroism spectroscopy and computer prediction from amino acid sequences is used to study conformations of wheat gluten proteins. The omega-gliadins are rich in beta-turns, but appear to have no alpha-helix or beta-sheet structures. Beta-Turns are also present in the repetitive central domain of the high molecular weight (HMW) subunits of glutenin. These beta-turns are regularly distributed, reflecting the regular primary structure. The N- and C-terminal domains of the HMW subunits are probably alpha-helical and contain only the cysteine residues so far detected in these proteins. In the alpha-gliadins and probably the beta- and gamma-gliadins, the beta-turns are concentrated in specific domains, notably a proline-rich repetitive domain close to the N-terminus. Other domains are rich in alpha-helix. The structure of the mammalian elastomeric protein elastin is reviewed and models for its elasticity discussed. One of these, the beta-spiral model of Urry and co-workers, is used as the basis for a model for gluten elasticity. We propose that the major elastic components of gluten are the HMW subunits of glutenin. The repetitive beta-turns in the central domain form an elastic beta-spiral, and these elastic monomers are assembled into gluten polymers by intermolecular disulfide bonds between the cysteine residues in the alpha-helical domains near the N- and C-termini.