INTRINSIC PHI,PSI PROPENSITIES OF AMINO-ACIDS, DERIVED FROM THE COIL REGIONS OF KNOWN STRUCTURES

Many different factors contribute to secondary structure propensities, including phi,psi preferences, side-chain interactions, steric effect s and hydrophobic tertiary contacts. To deconvolute these competing fa ctors, we have adopted a novel approach which quantifies the intrinsic phi,psi propensities for residues in coil regions (that is, residues not in alpha-helix and not in beta-strand). Comparisons of intrinsic p hi,psi propensities with their equivalent secondary structure propensi ties show that while correlations for helix are relatively weak, those for strand are much stronger. This paper describes our new phi,psi pr opensities and provides an explanation for the variations observed.