A NOTE ON CIRCULAR-DICHROIC-CONSTRAINED PREDICTION OF PROTEIN SECONDARY STRUCTURE

Circular dichroic (CD) spectra of bovine immunosuppressant binding pro teins FKBP12 and FKBP25, and cyclophilins (peptidylprolyl isomerases) A (bCyP-18) and B (bCyP-20), the immunophilins which selectively bind the clinically useful immunosuppressants FK506, rapamycin and cyclospo rin A, respectively, were analysed using the singular-value-decomposit ion algorithm augmented by a simplified variable selection method. The differences between the CD-estimated values of alpha-helix, beta-stru cture and beta-turn and those predicted by the Chou-Fasman algorithm w ere minimized using the CD data as constraints of an algorithm which u tilizes the method of hierarchical updating of quasi-equipotential pep tide segments of the Chou-Fasman prediction. The method allows one to correct the Chou-Fasman prediction of secondary structures in globular proteins.