title: Decarboxylases involved in polyamine biosynthesis and their inactivation by nitric oxide.
abstract: Polyamines are ubiquitous cellular components that are involved in normal and neoplastic growth. Polyamine biosynthesis is very highly regulated in mammalian cells by the activities of two key decarboxylases acting on ornithine and S-adenosylmethionine. Recent studies, which include crystallographic analysis of the recombinant human proteins, have provided a detailed knowledge of their structure and function. Ornithine decarboxylase is a PLP-requiring decarboxylase, whereas S-adenosylmethionine decarboxylase (AdoMetDC) contains a covalently bound pyruvate prosthetic group. Both enzymes have a key cysteine residue, which is involved in protonation of the Schiff base intermediate C(alpha) to form the product. These residues, Cys360 in ornithine decarboxylase (ODC) and Cys82 in AdoMetDC, react readily with nitric oxide (NO), which is therefore a potent inactivator of polyamine synthesis. The inactivation of these enzymes may mediate some of the antiproliferative actions of NO.
authors.affiliation: Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Hillary
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Pegg
mesh_terms: D012437:Adenosylmethionine Decarboxylase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000502:physiology*; D000818:Animals; D015317:Biogenic Polyamines / Q000096:biosynthesis*; D006801:Humans; D009569:Nitric Oxide / Q000502:physiology*; D009955:Ornithine Decarboxylase / Q000737:chemistry / Q000502:physiology*; D065108:Ornithine Decarboxylase Inhibitors; D013329:Structure-Activity Relationship
chemical_list: D015317:Biogenic Polyamines; D065108:Ornithine Decarboxylase Inhibitors; D009569:Nitric Oxide; D009955:Ornithine Decarboxylase; D012437:Adenosylmethionine Decarboxylase