Abstract
The neuropeptide kyotorphin (Tyr-Arg) was degraded by rat brain synaptosomes via a synaptic membrane-bound peptidase which was inhibited by bestatin but not by amastatin. The Km for kyotorphin was 8×10−6 M and the Ki for bestatin was 1×10−7 M. The kyotorphin-degrading enzyme was distinguished from at least one other dipeptide-hydrolyzing activity in synaptosomes which was inhibited by both bestatin and amastatin. Gel permeation chromatography of detergentextracted synaptosomes resulted in the separation of the dipeptide-hydrolyzing activities. A single kyotorphin-degrading enzyme peak was observed which had a Mr=52,000. The activity peak could degrade other dipeptides including Phe-Arg, a synaptic membrane-generated metabolic of bradykinin. The kyotorphin-degrading enzyme appears to be novel and can be distinguished from other known dipeptidases on the basis of substrate specificity, subcellular localization, and inhibition profile.
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Orawski, A.T., Simmons, W.H. Dipeptidase activities in rat brain synaptosomes can be distinguished on the basis of inhibition by bestatin and amastatin: Identification of a kyotorphin (Tyr-Arg)-degrading enzyme. Neurochem Res 17, 817–820 (1992). https://doi.org/10.1007/BF00969018
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DOI: https://doi.org/10.1007/BF00969018