1997 Volume 73 Issue 7 Pages 154-157
The three-dimensional structure of an enzyme, 2-hydroxyl-6-oxo-6-phenylhexa-2, 4-dienoic acid (HPDA) hydrolase (conventionally called BphD) from Rhodococcus sp. strain RHA1 has been solved by X-ray crystal structure analysis. This enzyme hydrolyzes one of the highly reactive intermediates, the meta cleavage product of the reaction catalyzed by 2, 3-dihydroxybiphenyl dioxygenase, in the metabolic pathway degrading biphenyl compounds including the notorious environmental pollutant PCBs (polychlorinated biphenyls). By virtue of this and several other enzymes, the biphenyl compounds including PCBs are finally introduced into the tricarboxylic acid cycle. The BphD enzyme is an oligomeric enzyme made up of eight identical subunits each of 285 amino acid residues. The subunit consists of two domains, α/β domain and α domain, between which the active site is located.
