Capping and alpha-helix stability.


The first and last four residues of alpha-helices differ from the rest by not being able to make the intrehelical hydrogen bonds between the backbone greater than C=O groups of one turn and the greater than NH groups of the next. Physico-chemical arguments and statistical analysis suggest that there is a preference for certain residues at the C and N termini (The C- and N-caps) that can fulfil the hydrogen bonding requirements. We have tested this hypothesis by constructing a series of mutations in the two N-caps of barnase (Bacillus amyloliquefaciens ribonuclease, positions Thr 6 and Thr 26) and determining the change in their stability. The N-cap is found to stabilize the protein by up to approximately 2.5 kcal mol(-1). The presence of a negative charge of the N-cap adds some 1.6 kcal mol(-1) of stabilization energy because of the interaction with the macroscopic electrostatic dipole of the helix. Study holds ProTherm entries: 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976 Extra Details: electrostatic dipole; barnase; protein stability;,alpha-helices; hydrogen bonding; physico-chemical

Submission Details

ID: XC84aLHs

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:18 p.m.

Version: 1

Publication Details
Serrano L;Fersht AR,Nature (1989) Capping and alpha-helix stability. PMID:2812029
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Ribonuclease P00648 RNBR_BACAM
97.3 Ribonuclease P35078 RN_BACCI