Specificity of an HPETE peroxidase from rat PMN

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · Prostaglandins; (United States)

DOI:https://doi.org/10.1016/0090-6980(88)90077-9· OSTI ID:6155262

Skoog, M T; Nichols, J S; Harrison, B L; Wiseman, J S

The 15,000xg supernatant of sonicated rat PMN contains 5-lipoxygenase that converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and leukotriene A4 and an HPETE peroxidase that catalyzes reduction of the 5-HPETE. The specificity of this HPETE peroxidase for peroxides, reducing agents, and inhibitors has been characterized to distinguish this enzyme from other peroxidase activities. In addition to 5-HPETE, the HPETE peroxidase will catalyze reduction of 15-hydroperoxyeicosatetraenoic acid, 13-hydroperoxyoctadecadienoic acid, and 15-hydroperoxy-8,11,13-eicosatrienoic acid, but not cumene or t-butylhydroperoxides. The HPETE peroxidase accepted 5 of 11 thiols tested as reducing agents. However, glutathione is greater than 15 times more effective than any other thiol tested. Other reducing agents, ascorbate, NADH, NADPH, phenol, p-cresol, and homovanillic acid, were not accepted by HPETE peroxidase. This enzyme is not inhibited by 10 mM KCN, 2 mM aspirin, 2 mM salicylic acid, or 0.5 mM indomethacin. When 5-(14C)HPETE is generated from (14C)arachidonic acid in the presence of unlabeled 5-HPETE and the HPETE peroxidase, the 5-(14C)HETE produced is of much lower specific activity than the (14C)arachidonic acid. This indicates that the 5-(14C)HPETE leaves the active site of 5-lipoxygenase and mixes with the unlabeled 5-HPETE in solution prior to reduction and is a kinetic demonstration that 5-lipoxygenase has no peroxidase activity. Specificity for peroxides, reducing agents, and inhibitors differentiates HPETE peroxidase from glutathione peroxidase, phospholipid-hydroperoxide glutathione peroxidase, a 12-HPETE peroxidase, and heme peroxidases. The HPETE peroxidase could be a glutathione S-transferase selective for fatty acid hydroperoxides.

• Research Organization: Merrell Dow Research Institute, Cincinnati, OH (USA)
• OSTI ID: 6155262
• Journal Information: Prostaglandins; (United States), Journal Name: Prostaglandins; (United States) Vol. 36:3; ISSN PRGLB
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ARACHIDONIC ACID
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
DRUGS
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
GLUTATHIONE
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEUKOCYTES
MATERIALS
MEMBRANES
MONOCARBOXYLIC ACIDS
NEUTROPHILS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PEPTIDES
PERITONEUM
PEROXIDASES
POLYPEPTIDES
PROTEINS
RADIOPROTECTIVE SUBSTANCES
REAGENTS
SEROUS MEMBRANES
SPECIFICITY
TRACER TECHNIQUES