Inhibition of lactoperoxidase by its own catalytic product: crystal structure of the hypothiocyanate-inhibited bovine lactoperoxidase at 2.3-A resolution.

ABSTRACT: To the best of our knowledge, this is the first report on the structure of product-inhibited mammalian peroxidase. Lactoperoxidase is a heme containing an enzyme that catalyzes the inactivation of a wide range of microorganisms. In the presence of hydrogen peroxide, it preferentially converts thiocyanate ion into a toxic hypothiocyanate ion. Samples of bovine lactoperoxidase containing thiocyanate (SCN(-)) and hypothiocyanate (OSCN(-)) ions were purified and crystallized. The structure was determined at 2.3-A resolution and refined to R(cryst) and R(free) factors of 0.184 and 0.221, respectively. The determination of structure revealed the presence of an OSCN(-) ion at the distal heme cavity. The presence of OSCN(-) ions in crystal samples was also confirmed by chemical and spectroscopic a

SUBMITTER: Singh AK 

PROVIDER: S-EPMC2716474 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature