Probing protein conformation with a minimal photochemical reagent.

ABSTRACT: 3H-diazirine (3H-DZN), a photoreactive gas similar in size to water, was used to probe the topography of the surface and inner space of proteins. On photolysis 3H-DZN generates 3H-methylene carbene, which reacts unselectively with its molecular cage, inserting even into C-H bonds. Labeling of bovine alpha-lactalbumin (alpha-LA, MW: 14,200) with 1 mM (3)H-DZN yielded 0.0041 mol CH2/mol of protein, in agreement with the expectation for an unspecific surface-labeling phenomenon. The cooperative urea-induced unfolding of alpha-LA, as monitored by the extent of 3H-methylene labeling, agrees with that measured by circular dichroism spectroscopy in the far and near ultraviolet regions. At 8 M urea, the unfolded state U was labeled 25-30% more than the native state N primarily because of the incre

SUBMITTER: Craig PO 

PROVIDER: S-EPMC2373615 | biostudies-literature | 2002 Jun

REPOSITORIES: biostudies-literature