A Statistical Analysis of the PPII Propensity of Amino Acid Guests in Proline-Rich Peptides  Mahmoud Moradi, Volodymyr Babin, Celeste Sagui, Christopher Roland  Biophysical Journal  Volume 100, Issue 4, Pages 1083-1093 (February 2011) DOI: 10.1016/j.bpj.2010.12.3742 Copyright © 2011 Biophysical Society Terms and Conditions

Figure 1 Typical examples of Ramachandran plots for different residues (a) P1 in PPP peptide, (b) P3 in PPP, PAP, PGP, and PVP, (c) P6 in PPP, PAP, PPP′, and PAP′, and (d) ending Gly and Tyr (boldface) in PPP and PAP. Note that the definitions of the areas F, β, αR, and αL are highlighted in panel a. Each pixel represents a 1° × 1° bin in the Ramachandran plot and its intensity represents the number of times visited in our sampling, scaled (as given on right) from 0% (white) to 0.09% (black) of the whole population (105). Biophysical Journal 2011 100, 1083-1093DOI: (10.1016/j.bpj.2010.12.3742) Copyright © 2011 Biophysical Society Terms and Conditions

Figure 2 Ramachandran plots of all 20 guest residues in PXP peptides. See Fig. 1 for the definitions. Note that histidine in PHP is assumed to be protonated. Biophysical Journal 2011 100, 1083-1093DOI: (10.1016/j.bpj.2010.12.3742) Copyright © 2011 Biophysical Society Terms and Conditions

Figure 3 Experimental values (25) of the PPII content plotted against ΔΔG, computed from the odds ratio of PPII for the P3 and X residues in PXP peptides (X ≠ P,Y,W). Labels identify the guest amino acids. Simulation data for PYP and PWP is not shown, because no experimental data is available for these peptides. Data for PPP is also excluded because of the substantive differences between the P-P correlation as compared to the P-X (X ≠ P) correlation. The correlation coefficient is R = 0.85. Note that the histidine in PHP peptide is assumed to be protonated. Biophysical Journal 2011 100, 1083-1093DOI: (10.1016/j.bpj.2010.12.3742) Copyright © 2011 Biophysical Society Terms and Conditions