Degradation of prolylleucylglycinamide (MIF) by mouse brain.
Prolylleucylglycinamide (MIF) at 1.0 mM concentration and pH 7.0 was hydrolyzed by mouse brain homogenate at a rate of 140 nmol/mg protein/hr. Nearly all of this activity can be accounted for by the action of two enzymes, both of which cleave Pro and Leu sequentially from the N-terminus of MIF. At pH 7.0 the predominant enzyme is arylamidase, inhibited by puromycin (1 mM) and Mn2+ (2.5 mM). At pH 8.5, in the presence of Mn2+, a second enzyme with a higher potential activity (570 nmol/mg protein/hr) was observed. While the arylamidase is primarily localized in the cytosol, the Mn2+-stimulated enzyme is equally divided between soluble and particulate fractions. Because of its ability to cleave leucinamide, its high pH optimum, and its Mn2+ dependence, it can be classified as a leucine aminopeptidase (LAP). In its substrate specifically and its preference for Mn2+ over Mg2+ it resembles the LAP from connective tissue more than that from other sources.
D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002848:Chromatography, DEAE-Cellulose; D005470:Fluorometry; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007931:Leucyl Aminopeptidase / Q000378:metabolism; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000378:metabolism; D008345:Manganese / Q000502:physiology; D051379:Mice; D011691:Puromycin / Q000494:pharmacology
D008345:Manganese; C024569:pareptide; D011691:Puromycin; D009075:MSH Release-Inhibiting Hormone; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase