Structural evidence of substrate specificity in mammalian peroxidases: structure of the thiocyanate complex with lactoperoxidase and its interactions at 2.4 A resolution.

ABSTRACT: The crystal structure of the complex of lactoperoxidase (LPO) with its physiological substrate thiocyanate (SCN(-)) has been determined at 2.4A resolution. It revealed that the SCN(-) ion is bound to LPO in the distal heme cavity. The observed orientation of the SCN(-) ion shows that the sulfur atom is closer to the heme iron than the nitrogen atom. The nitrogen atom of SCN(-) forms a hydrogen bond with a water (Wat) molecule at position 6'. This water molecule is stabilized by two hydrogen bonds with Gln(423) N(epsilon2) and Phe(422) oxygen. In contrast, the placement of the SCN(-) ion in the structure of myeloperoxidase (MPO) occurs with an opposite orientation, in which the nitrogen atom is closer to the heme iron than the sulfur atom. The site corresponding to the positions of Gln(423)

SUBMITTER: Sheikh IA 

PROVIDER: S-EPMC2685666 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature