Direct observation of photolysis-induced tertiary structural changes in hemoglobin.

ABSTRACT: Human Hb, an alpha2beta2 tetrameric oxygen transport protein that switches from a T (tense) to an R (relaxed) quaternary structure during oxygenation, has long served as a model for studying protein allostery in general. Time-resolved spectroscopic measurements after photodissociation of CO-liganded Hb have played a central role in exploring both protein dynamical responses and molecular cooperativity, but the direct visualization and the structural consequences of photodeligation have not yet been reported. Here we present an x-ray study of structural changes induced by photodissociation of half-liganded T-state and fully liganded R-state human Hb at cryogenic temperatures (25-35 K). On photodissociation of CO, structural changes involving the heme and the F-helix are more marked in the a

SUBMITTER: Adachi S 

PROVIDER: S-EPMC165826 | biostudies-literature | 2003 Jun

REPOSITORIES: biostudies-literature