ISSN:
0739-4462
Keywords:
neuropeptide formation
;
inhibition of amidating enzyme
;
glycyl peptide hydroxylation
;
Chemistry
;
Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
Peptidylglycine α-hydroxylating monooxygenase (PHM), an enzyme involved in formation of neuropeptides with a C-terminal amide functionality in mammals and amphibians, was isolated from the head of an invertebrate, the honeybee, Apis mellifera, and purified 220-fold in 1% overall yield. The bee PHM has a molecular weight of 71,000, is membrane associated but can be solubilized with a detergent (n-octyl-β-D-glucopyranoside), and cross-reacts with rabbit antibodies generated toward bacterially expressed rat PHM. In the presence of copper, oxygen, and ascorbic acid, the enzyme hydroxylates model tripeptides such as dansyl-L-Phe-L-Phe-Gly on the methylene carbon of the glycine residue with retention of configuration. Using this tripeptide as substrate, the Km is 1.7 μM and the Vmax is 2.3 nmol • μg-1 • h-1. Treatment of the insect PHM with D-Phe-L-Phe-D-vinylglycine, a substrate analogue and mechanism-based inactivator of PHM from pig pituitary, results in irreversible loss of activity. The diastereomeric analogue, D-Phe-L-Phe-L-vinylglycine, is only a competitive inhibitor (lC50 = 320 μM). © 1994 Wiley-Liss, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/arch.940260104
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