PMID: 6108995Aug 1, 1980Paper

Degradation of melanotropin inhibiting factor by brain

Journal of Neurochemistry
K S HuiA Lajtha

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
Dec 1, 1979·Neurochemical Research·K S HuiA Lajtha
Aug 1, 1979·Journal of Neurochemistry·M OrlowskiS Wilk
Feb 1, 1978·Journal of Neurochemistry·K S Hui, A Lajtha
Nov 1, 1976·Life Sciences·J M van Ree, D de Wied
Jul 1, 1971·Journal of Comparative and Physiological Psychology·C A SandmanA J Kastin
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May 1, 1974·Journal of Neurochemistry·N MarksA Lajtha
May 1, 1962·Journal of Neurochemistry·L L UZMANM K RUMLEY

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Citations

Dec 1, 1982·Pharmacology, Biochemistry, and Behavior·J E ZadinaD H Coy
Jan 1, 1984·Neurochemistry International·N MarksD H Coy
Dec 1, 1981·Brain Research Bulletin·M G LucianoD H Coy
Jan 1, 1982·Journal of Neurochemistry·D de WildtA Witter

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