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Polypeptide chain fold; Phylogenetic relationship; Significance of a similarity; Mean Cα distance
Abstract:
Structural similarities between proteins with no amino acid sequence homology either indicate a phylogenetic relationship, or they are merely the expression of a physically preferred way of folding a polypeptide chain. It is shown that one can distinguish between these alternatives by evaluating the “significance of the similarity”. Such significances have been derived for comparison between chain folds containingβ-pleated sheets (Schulz and Schirmer, 1974; Richardson et al., 1976; Sternberg and Thornton, 1976). An extension of this method to comparisons between any two chain folds is outlined here.
