Populations of the Minor α-Conformation in AcGXGNH2 and the α-Helical Nucleation Propensities

作者：Zhou, Yanjun; He, Liu; Zhang, Wenwen; Hu, Jingjing; Shi, Zhengshuang^*

来源：Scientific Reports, 2016, 6(1): 27197.

DOI：10.1038/srep27197

• POLYPROLINE-II HELIX
• PEPTIDE BACKBONE CONFORMATIONS
• RAMAN OPTICAL-ACTIVITY
• AMINO-ACIDS
• FOLDING PROTEINS
• DIHEDRAL ANGLES
• SIDE-CHAINS
• HOST-GUEST
• ALANINE
• TRANSITION

Intrinsic backbone conformational preferences of different amino acids are important for understanding the local structure of unfolded protein chains. Recent evidence suggests alpha-structure is relatively minor among three major backbone conformations for unfolded proteins. The alpha-helices are the dominant structures in many proteins. For these proteins, how could the alpha-structures occur from the least in unfolded to the most in folded states? Populations of the minor alpha-conformation in model peptides provide vital information. Reliable determination of populations of the alpha-conformers in these peptides that exist in multiple equilibriums of different conformations remains a challenge. Combined analyses on data from AcGXPNH(2) and AcGXGNH(2) peptides allow us to derive the populations of PII, beta and a in AcGXGNH(2). Our results show that on average residue X in AcGXGNH2 adopt PII, beta, and a 44.7%, 44.5% and 10.8% of time, respectively. The contents of alpha-conformations for different amino acids define an alpha-helix nucleation propensity scale. With derived PII, beta and alpha-contents, we can construct a free energy-conformation diagram on each AcGXGNH(2) in aqueous solution for the three major backbone conformations. Our results would have broad implications on early-stage events of protein folding.

• 出版日期2016-6-3
• 单位华中科技大学