Purification and characterization of enkephalinase B from rat brain membrane.
Enkephalinase B from rat brain membrane which hydrolyzes enkephalin at the Gly-Gly bond was purified about 9400-fold to apparent electrophoretic homogeneity. The enzyme, which has a molecular weight of 82,000, consists of a single polypeptide chain. The enzyme has a pH optimum of 6.0-6.5 and is stable in the neutral pH region. The Km values of Met-enkephalin and Leu-enkephalin for this enzyme were 5.3 X 10(-5) M and 5.0 X 10(-5) M, respectively. The enzyme was inactivated by metal chelators, EDTA and o-phenanthroline and restored by the addition of divalent metal ions, Zn2+, Mn2+ or Fe2+, but was not inhibited by bestatin, amastatin, phosphoramidon or captopril. The enzyme hydrolyzed Met-enkephalin and Leu-enkephalin effectively. Although the enzyme belongs to the dipeptidyl aminopeptidase class, enkephalin-related peptides such as Leu-enkephalin-Arg, dynorphin (1-13) or alpha-endorphin and other biologically active peptides examined were hardly, or not at all, hydrolyzed. It was assumed that enkephalinase B functions mainly in enkephalin degradation in vivo.
Inaoka
Y
Y
Tamaoki
H
H
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002412:Cations / Q000494:pharmacology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D010450:Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism; D011480:Protease Inhibitors; D051381:Rats; D013379:Substrate Specificity
D002412:Cations; D004745:Enkephalins; D008565:Membrane Proteins; D010455:Peptides; D011480:Protease Inhibitors; D010450:Endopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C100152:dipeptidyl peptidase III