Abstract
Degradation of melanotropin inhibiting factor (MIF) was measured by fluorometry, using pareptide as an internal standard, following the separation of the dansyl derivatives of MIF and its metabolites by HPLc. MIF was not split by carboxypeptidases A and B, prolidase, or pyroglutamate aminopeptidase. It was hydrolyzed by leucine aminopeptidase, aminopeptidase M, and carboxypeptidase Y. Rat brain hydrolyzed 159 nmol of MIF per mg of protein per h; the activity was linear with enzyme concentration. Hydrolysis start from the N-terminal end, as shown by the appearance of proline as the first metabolite of the MIF degradation, followed by leucine, glycinamide, leucylglycine, and glycine. Activity in the rat brain regions was in the order striatum, medulla oblongata > cortex, hippocampus, midbrain > hypothalamus, cerebellum, and pituitary. The enzyme was mostly in the supernatant, with significant amounts in the myelin and synaptosomal fractions. MIF aminopeptidase could be separated from carboxypeptidase by centrifugation at 30,000 x g for 20 min and precipitation with 45--75% (NH4)2SO4. It showed pH optima in the alkaline range (8.25 and 8.75) and was inhibited by EDTA, EGTA, SQ 14,225, puromycin, bacitracin, and bestatin.
References
Jan 1, 1979·European Journal of Pharmacology·S Chiu, R K Mishra
Jul 30, 1979·Life Sciences·A J KastinD H Coy
Aug 1, 1979·Journal of Medicinal Chemistry·S BjörkmanH Sievertsson
Dec 1, 1979·Neurochemical Research·K S HuiA Lajtha
Jun 8, 1979·Brain Research·L B Hersh, J F McKelvy
Sep 15, 1978·Brain Research·K S Hui, A Lajtha
Nov 30, 1978·Nature·B MalfroyJ C Schwartz
Mar 1, 1979·Neuroscience Letters·B MalfroyJ C Schwartz
Aug 1, 1979·Journal of Neurochemistry·M OrlowskiS Wilk
Oct 29, 1979·Life Sciences·A GuyonJ C Schwartz
Feb 1, 1978·Journal of Neurochemistry·K S Hui, A Lajtha
Mar 26, 1976·Brain Research·E C GriffithsN White
Nov 1, 1976·Life Sciences·J M van Ree, D de Wied
Feb 21, 1975·Brain Research·E C GriffithsD T Holland
Jul 1, 1971·Journal of Comparative and Physiological Psychology·C A SandmanA J Kastin
Jun 1, 1972·Proceedings of the Society for Experimental Biology and Medicine·N Marks, R Walter
May 1, 1974·Journal of Neurochemistry·N MarksA Lajtha
Jan 1, 1974·Neuroendocrinology·T W ReddingA V Schally
Jan 1, 1973·Neuroendocrinology·T W ReddingA V Schally
May 2, 1980·Journal of Chromatography·K S HuiA Lajtha
May 1, 1962·Journal of Neurochemistry·L L UZMANM K RUMLEY
Citations
Dec 1, 1982·Pharmacology, Biochemistry, and Behavior·J E ZadinaD H Coy
Jan 1, 1982·Neurochemistry International·M E Celis, C Peña
Jan 1, 1984·Neurochemistry International·N MarksD H Coy
Dec 1, 1981·Brain Research Bulletin·M G LucianoD H Coy
Apr 1, 1982·Journal of Neurochemistry·J VerhoefA Witter
Jul 5, 1990·European Journal of Biochemistry·A Turzynski, R Mentlein
Jan 1, 1982·Journal of Neurochemistry·D de WildtA Witter