Conservativity of three-dimensional structures of alpha-, beta- and gamma-interferons

Using the method of estimation of alpha-helical and beta-folded types of secondary structure from amino acid composition, it has been established that interferon-gamma (IFN-gamma) contains about 50-70% of alpha-helical and no more than 10-20% of beta-structure. The same result was obtained using empirical and stereochemical rules for the prediction of protein secondary structure from amino acid sequence. Packing of alpha-helical segments of IFN-gamma into 1 of the 2 three-dimensional structures previously suggested for IFN-alpha and IFN-beta, allowed to detect high conservativity of the hydrophobic core of the proteins compared. On this basis a tentative conclusion has been drawn that all interferons have, in general features, a similar globular alpha-helical conformation.