BINDING MODE OF BENZHYDROXAMIC ACID TO ARTHROMYCES-RAMOSUS PEROXIDASESHOWS BY X-RAY CRYSTALLOGRAPHIC ANALYSIS OF THE COMPLEX AT 1.6 ANGSTROM RESOLUTION

The crystal structure of Arthromyces ramosus peroxidase (ARP) in compl ex with benzhydroxamic acid (BHA) its determined by X-ray analysis at 1.6 Angstrom shows unambiguously how BHA binds to ARP, BHA is located in the distal heme pocket. Its functional groups are held by three hyd rogen bonds to His(56)N(epsilon), Arg(52)N(epsilon), and Pro(154)O, bu t are too far away to interact with the heme iron, The aromatic ring o f BHA is positioned at the entrance of the channel to the heme pocket, approximately parallel to the heme group, Most water molecules at the active site of the native enzyme are replaced by BHA, leaving a ligan d, probably a water molecule, at the sixth position of the heme, Resul ts are compared with spectroscopic data. (C) 1997 Federation of Europe an Biochemical Societies.