Left helix of polyproline Ii type and genesis of beta-structures in spidroins 1 and 2 and their recombinant analogs
Esipova, N.G.; Ragulina, L.E.; Davydova, L.I.; Lobachev, V.M.; Makeev, V.I.; Bogush, V.G.; Tumanian, V.G.; Debabov, V.G.
Biofizika 54(3): 389-395
2009
ISSN/ISBN: 0006-3029 PMID: 19569497 Document Number: 629427
The distribution of secondary structures along the polypeptide chains of spider proteins spidroins 1 and 2 and their recombinant analogs has been studied by statistical methods. It was found that these proteins in the monomolecular form contain only trace amounts of beta-structures. At the same time, the regions of the sequence including Ala and Gly are predicted as helical-containing (with alpha-helices and left-helices of polyproline II type). An analysis of literature data and our data obtained in this study shows that the main conformation of the polypeptide chain solutions of spidroins 1 and 2 and their recombinant analogs in water solutions is the left-helix of polyproline II type with some contaminations of alpha-helices and a very small share of beta-structures. The transition to the state with extended conformations, which are peculiar to mature filaments of spider webs, requires the dehydration of the polypeptide chain backbone. Thus, the genesis of beta-structure in spider web proteins is determined by the conditions of conformation transitions between the main regular conformations of the polypeptide chain backbone.