Secondary Structure Prediction of Chicken Egg White Ovomucoid

Abstract

The secondary structure of chicken egg white ovomucoid (186 residues) was predicted from the amino acid sequence by the method of Chou and Fasman (P. Y. Chou and G. D. Fasman, Biochemistry, 13, 222 (1974)). The ovomucoid α-helix regions were predicted by the method of Lewis et al. (P. N. Lewis et al., Proc. Natl. Acad. Sci. U.S., 65, 810 (1970)). The relative composition of the secondary structure obtained by the former method was: α-helix (7 regions) 27 %, β-structure (10 regions) 33 %, β-turn (11 regions) 23% and random coil 17 %. In the predicted conformation, there were some α-helical and β-structure segments that tended to be segregated along the polypeptide chain. These results indicate that the ovomucoid may be classified into the α+β type protein group and that the reactive site (Arg ⁸⁹1Ala⁹⁰) of trypsin inhibition is probably situated at the C-terminal β-structure end. In comparisons of the predicted structures of the three domains in ovomucoid, domains I and II were suggested to be partially homologous to one another and not to domain III.