Aminopeptidase activity in rat brain synaptosomes - 2-mercaptoethanol stimulation and Arg-vasopressin degradation
Rat brain synaptic plasma membranes contain an amastatin-inhibited aminopeptidase activity which degrades Arg-vaso-pressin (AVP). The pH optimum for AVP cleavage was found to be 6.8, similar to that reported for oxytocin. The ability of other peptides and arylamides such as oxytocin, Tyr-Phe-Met-Arg-Phe-NH/sub 2/ and Arg-Arg-..beta..NA to inhibit cleavage of (/sup 3/H-Tyr/sup 2/)-AVP suggests that the enzyme may not be specific for AVP. The AVP-cleaving activity has been solubilized and partially characterized. Synaptosomes were lysed with hypotonic buffer, washed, and extracted with 1% Nonidet P-40 detergent. The solubilized protein was chromatographed by gel filtration HPLC on Superose 6. A single peak of activity was found with a M.W. = 117,000 which could hydrolyze 1mM Ala-..beta..NA, Arg-..beta..NA, Arg-Arg-..beta..NA, Phe-Met and Phe-Arg as well as slowly cleave AVP with the ultimate release of /sup 3/H-Tyr. 2-Mercaptoethanol (3.9mM) (ME) stimulated activity 3.6 to 6.6-fold for arylamide and dipeptide substrates, but 35-fold for labelled AVP, possibly owing to reduction of the AVP disulfide bond. All activities in the presence of ME were completely inhibited by 0.2mM amastatin.
- Research Organization:
- Loyola Univ. Medical Center, Maywood, IL
- OSTI ID:
- 7189431
- Report Number(s):
- CONF-8604222-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMINOPEPTIDASES
ENZYME ACTIVITY
VASOPRESSIN
METABOLISM
BRAIN
CELL MEMBRANES
LIQUID COLUMN CHROMATOGRAPHY
NERVES
OXYTOCIN
PEPTIDES
RATS
RESPONSE MODIFYING FACTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CHROMATOGRAPHY
ENZYMES
HORMONES
HYDROLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MEMBRANES
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PEPTIDE HYDROLASES
PITUITARY HORMONES
PROTEINS
RODENTS
SEPARATION PROCESSES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques