A note on circular-dichroic-constrained prediction of protein secondary structure

Abstract

Circular dichroic (CD) spectra of bovine immunosuppressant binding proteins 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 cyclosporin A, respectively, were analysed using the singular-value-decomposition algorithm augmented by a simplified variable selection method. The differences between the CD-estimated values of α-helix, β-structure and β-turn and those predicted by the Chou-Fasman algorithm were minimized using the CD data as constraints of an algorithm which utilizes the method of hierarchical updating of quasi-equipotential peptide segments of the Chou-Fasman prediction. The method allows one to correct the Chou-Fasman prediction of secondary structures in globular proteins.