A STATISTICAL ANALYSIS OF THE CORRELATION OF AMINO ACID RESIDUES IN β-REGIONS OF GLOBULAR PROTEINS

Abstract

Starting out with the null hypothesis that the amino acid residues are.. distributed without any preference for allY parts of B-regions, a statistical analysis is performed on the amine acid r{?sidues occurring 'at the N-termillal, 'C-terminal, and in the inner'{J-region s, of 21 globular proteins with' a total (f 3523 residues. The observe{l fl-,regi~ns are take~fron'l x-ray data. Statistically reliable. dijJerelzces in th~ individual amino acid content' of {J-regions have revealed the following feaiures:' Ala"and' Prp 'show an above-average tendency while Cys shows a below-average tendency to be'at the N~terminal f3-regions'i, Val, Leu, lie, and Phe prefer- the inner {I-regiOns,' wli,i1e Pro, Asn, and Lys show a below average preference tl be in the iimer {J-regions.Highly hydrophobic residues are found to prefer the inner f3-region~, »!eakly hydrophobic and charged residues prefer the non-fJ-·regions.'Phe results of this study ollly partially suppo rt the rules due to Cho u and Fasman for prediction of protein conformation and h~n ce indicate the need for -their
modification.