Propensities of aromatic amino acids versus leucine and proline to induce residual structure in the denatured-state ensemble of iso-1-cytochrome c.

ABSTRACT: Histidine-heme loop formation in the denatured state of a protein is a sensitive means for probing residual structure under unfolding conditions. In this study, we use a host-guest approach to investigate the relative tendencies of different amino acids to promote residual structure under denaturing conditions. The host for this work is a 6-amino-acid insert of five alanines, followed by a lysine engineered immediately following a unique histidine near the N-terminus of yeast iso-1-cytochrome c. We substitute the fourth alanine in this sequence HAAAXAK (with X=Trp, Phe, Tyr, and Leu). The effects of proline are tested with substitutions at positions 1 and 5 in the insert (HPAAAAK and HAAAAPK, respectively). Thermodynamic studies on His-heme loop formation in 3 M guanidine hydrochloride rev

SUBMITTER: Finnegan ML 

PROVIDER: S-EPMC3025290 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature