Substance P inactivating enzymes in human cerebrospinal fluid.
The Km and Vmax values were determined for enzymes in human lumbar cerebrospinal fluid (CSF) that inactivate synthetic substance P (SP = RPKPQQFFGLM-NH2) and produce metabolic products. For the human lumbar CSF samples analyzed in this study, Km = 2.24 +/- 0.93 mM and Vmax = 0.113 +/- 0.035 nmol/ml/min (n = 10; mean +/- SEM) for the rate of decrease of SP. HPLC analysis of the incubated synthetic peptide fragments demonstrated that the primary enzymatically produced fragment is SP(3-11), with minor amounts in decreasing order of SP(1-4), SP(1-7), and SP(1-9). Electrospray ionization mass spectrometry (ESI-MS) confirmed the appropriate molecular weights for the four peptides, SP(3-11), SP(1-4), SP(1-7), and SP(1-9). These data demonstrate that the primary enzyme in human lumbar CSF that acts on synthetic SP is a post-proline cleaving enzyme (PPCE).
Kaneko
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Charles B. Stout Neuroscience Mass Spectrometry Laboratory, University of Tennessee, Memphis 38163.
Wood
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Crouch
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Desiderio
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D000595:Amino Acid Sequence; D004798:Enzymes / Q000134:cerebrospinal fluid*; D006801:Humans; D008161:Lumbosacral Region; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D013373:Substance P / Q000037:antagonists & inhibitors*
D004798:Enzymes; D013373:Substance P