Dynamics of ligand rebinding to unfolded MbCO by guanidine HCl.

ABSTRACT: Femtosecond vibrational spectroscopy was used to probe a functionally important dynamics and residual structure of myoglobin unfolded by 4 M guanidine HCl. The spectra of the dissociated CO indicated that the residual structure of unfolded myoglobin (Mb) forms a few hydrophobic cavities that could accommodate the dissociated ligand. Geminate rebinding (GR) of CO to the unfolded Mb is three-orders-of-magnitude faster and more efficient than the native Mb but similar to a model heme in a viscous solvent, suggesting that the GR of CO to heme is accelerated by the longer retention of the dissociated ligand near the Fe atom by the poorly-structured protein matrix of the unfolded Mb or viscous solvent. The inefficient GR of CO in native Mb, while dissociated CO is trapped in the primary heme poc

SUBMITTER: Park J 

PROVIDER: S-EPMC2480693 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature