The heme-binding properties of prostaglandin synthetase from sheep vesicular gland

• Published in: The Journal of biological chemistry Vol. 256; no. 19; pp. 10018 - 10022
• Main Authors: Roth, G J, Machuga, E T, Strittmatter, P
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10-10-1981
• Subjects: Animals; Binding Sites; Heme - metabolism; Macromolecular Substances; Male; Molecular Weight; prostaglandin synthase; Prostaglandin-Endoperoxide Synthases - metabolism; Protein Binding; Seminal Vesicles - enzymology; Sheep; Spectrophotometry; vesicular gland
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)68733-8

Purified, apoprostaglandin synthetase was prepared from sheep vesicular gland and studied in terms of its heme-binding properties.
The enzyme binds a single heme group per enzyme monomer, Mr = 70,000. When reconstituted with heme, the enzyme has an absorption
maximum at 412 nm and an absorption coefficient, epsilon 412 nm, of 120 mM-1 cm-1. The binding of heme to the apoenzyme was
accompanied by a proportional increase in enzyme activity up to the point of heme-binding saturation. This reconstituted holoenzyme
forms prostaglandin H2 from arachidonate. We conclude that prostaglandin synthetase possesses the heme-binding properties
of a "typical" heme protein and that a single heme group mediates both the oxygenase and the peroxidase activities of the
enzyme.