Polyproline helices in protein structures: A statistical survey.
A statistical survey of polyproline II (PPII) helices extracted from protein crystal structures is here reported. The average hydrophobicity of these helices is intermediate between those displayed by beta-strands and coil regions and is similar to that of alpha-helices. PPII helices with amphipathic properties have been identified and classified. Amino acid propensities for PPII helices derived in this study differ significantly from those previously reported. They show a little albeit significant correlation with propensities for alpha-helices whereas they are fully non-correlated to propensities for beta-sheets. Finally, PPII propensities have been correlated with amino acid frequencies in structural proteins, such as collagen and extensins.
Berisio
Rita
R
Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16. I-80134 Napoli, Italy.
Loguercio
Salvatore
S
De Simone
Alfonso
A
Zagari
Adriana
A
Vitagliano
Luigi
L
D000465:Algorithms; D019295:Computational Biology / Q000379:methods; D030562:Databases, Protein / Q000706:statistics & numerical data; D015233:Models, Statistical; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D010455:Peptides; C011083:polyproline