Our understanding of the factors stabilizing alpha-helical structure has been greatly enhanced by the study of model alpha-helical peptides. However, the relationship of these results to the folding of helices in intact proteins is not well characterized. Helix propensities measured in model peptides are not in good agreement with those from proteins. In order to address these questions, we have measured helix propensities in the alpha-helix of ribonuclease T1 and a helical peptide of identical sequence. We have previously demonstrated excellent agreement between peptide and protein for the nonpolar amino acids [Myers, J. K., Pace, C. N., and Scholtz, J. M. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 2833-2837]. Most other amino acids also show good agreement, although certain polar amino acids are exceptions. Helix propensities measured in the ribonuclease T1 peptide/protein are compared with those measured in other systems. Reasonable agreement is found between most systems; however, our propensities differ substantially from those measured in several model peptide systems. Alanine-based peptides overestimate the propensity differences by a factor of 2, and host/guest experiments underestimate them by a factor of 2-3. Study holds ProTherm entries: 2339, 2340, 2341, 2342, 2343, 2344, 2345, 2346, 2347, 2348, 2349, 2350, 2351, 2352, 2353, 2354, 2355, 2356, 2357, 2358, 2359, 2360, 2361, 2362, 2363 Extra Details: ddG values are relative to pseudo wild type Ribonuclease T1, (G23A) Ribonuclease T1; alpha-helical; Helix propensities; peptides
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:18 p.m.
|Number of data points||75|
|Proteins||Guanyl-specific ribonuclease T1 ; Guanyl-specific ribonuclease T1|
|Assays/Quantities/Protocols||Experimental Assay: Cm buffers:MOPS: 30 mM, pH:7.0 ; Experimental Assay: m buffers:MOPS: 30 mM, pH:7.0 ; Experimental Assay: ddG buffers:MOPS: 30 mM, pH:7.0 ; Experimental Assay: Cm pH:2.5, buffers:glycine: 30 mM ; Experimental Assay: m pH:2.5, buffers:glycine: 30 mM ; Experimental Assay: ddG pH:2.5, buffers:glycine: 30 mM|
|Libraries||Mutations for sequence ACDYTCGSNCYSSSDVSTAQAAGYQLHEDGETVGSNSYPHKYNNYEGFDFSVSSPYYEWPILSSGDVYSGGSPGADRVVFNENNQLAGVITHTGASGNNFVECT|