Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purification and kinetic characterization of cholinesterase from blood plasma (pseudocholinesterase; butyrylcholinesterase: EC 3.1.1.8) is described. The hydrolysis of the artificial peptide substrate Lys-Pro-p-nitroanilide served as a model of the second step in degradation of substance P by dipeptidyl peptidase IV. The substrate is hydrolyzed by a gel-electrophoretic homogeneous cholinesterase preparation with a reaction rate of 5.8 mumol/min X mg and a KM value of 0.12 mmol/l. The proteolytic reaction could not be affected with typical cholinesterase inhibitors NaF and dibucain. On the other hand Lys (pNO2-Z)-Pro and a specific suicide substrate (diacylhydroxylamine derivative) inhibit the activity in a manner analogous to dipeptidyl peptidase IV. Though these active site-directed inhibitors also influenced the benzoylcholine hydrolyzing activity of serum cholinesterase, we conclude from the data that dipeptidyl peptidase IV was the true Lys-Pro-p-nitroanilide cleaving activity. Furthermore, the conclusion can also be drawn that hydrolysis of substance P reported by Lockridge 1982 is caused by the contamination that cannot be completely separated from the esterase during the purification method used.
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PMID:Contamination of highly purified human serum cholinesterase by dipeptidyl peptidase IV causing hydrolysis of substance P. 243 Mar 7

Highly purified human serum cholinesterase (EC 3.1.1.8, also known as pseudocholinesterase and butyrylcholinesterase) had peptidase activity toward substance P. Digestion of substance P was monitored by high performance liquid chromatography, which separated three product peptides. The cleavages occurred sequentially. The first peptide to appear as Arg1-Pro2. The Km for this hydrolysis was 0.3 mM; maximum activity was 7.9 nmol min-1 mg-1 of protein, which corresponded to a turnover number of 0.6 min-1. A second cleavage yielded Lys3-Pro4. A third cleavage occurred at the C-terminal, where the amide was removed from Met11 to yield a peptide containing residues 5-11. Both the peptidase and esterase activities of the enzyme were completely inhibited by the anticholinesterase agent, diisopropylfluorophosphate. Substance P inhibited the hydrolysis of benzoylcholine (a good ester substrate) with a KI of 0.17 mM, indicating that substance P interacted with cholinesterase rather than with a trace contaminant. Peptidase and amidase activities for serum cholinesterase are novel activities for this enzyme. It was demonstrated previously that the related enzyme acetylcholinesterase (EC 3.1.1.7) catalyzed the hydrolysis of substance P, but at entirely different cleavage sites from those reported in the present work. Since butyrylcholinesterase is present in brain and muscle, as well as in serum, it may be involved in the physiological regulation of substance P.
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PMID:Substance P hydrolysis by human serum cholinesterase. 617 30

Neutral endopeptidase 24.11 (NEP; "enkephalinase") may inactivate a number of centrally active neuropeptides including the enkephalins and substance P. In most areas of the central nervous system, the cell types which express NEP activity are not known. The hypoglossal nucleus (N.XII) was selected as a model system to characterize the cytochemical localization of NEP. The effect of hypoglossal nerve axotomy upon the distribution of NEP activity in the hypoglossal nucleus was compared to the effect upon cholinergic markers, the mu opiate receptor, and the enkephalins. By use of a fluorescence histochemical method, NEP was localized at all levels of N.XII to the soma and proximal processes of the majority of the apparent motor neurons in the nucleus. Fluorescent double-labeling studies revealed the presence of numerous enkephalinergic varicosities which localized to the neuropil surrounding NEP-stained motor neurons. To determine whether NEP was synthesized by these motor neurons, 18 rats received a unilateral transection of the hypoglossal nerve. A pronounced decrease in NEP staining in N.XII was observed on the operated side as early as 3 days following axotomy. This decrease persisted at all levels of the nucleus for about 5 weeks. By 7 weeks, the staining between the control and operated sides was indistinguishable. By contrast, there was no apparent change in the density or distribution of enkephalin-immunoreactive varicosities in five animals examined 6 to 32 days following axotomy. Radioligand binding of [3H]DAMGO to the mu-opiate receptor in N.XII was studied in 20 animals by quantitative autoradiography at 2, 6, and 11 days after axotomy. No significant changes in the level of radioligand binding to the mu-receptor were detected in response to axotomy. In contrast to the opiate system, the cholinergic enzymes choline acetyltransferase, acetylcholinesterase, and pseudocholinesterase showed a coordinate decrease in motor neuron-associated staining on the operated side of N.XII at 3, 6, and 11 days following axotomy which paralleled the decrease in NEP staining. By contrast, the lysosomal enzyme marker, acid phosphatase, showed a pronounced increase in staining on the operated side. The results of this study are consistent with the synthesis of NEP by cholinergic N.XII motor neurons and indicates that the enkephalins and NEP in N.XII are closely associated, but derive from separate neuronal populations. The widespread overlap in the distribution of NEP-stained motor neurons and enkephalinergic varicosities in N.XII provides additional anatomical support for a potential role for NEP in the inactivation of centrally active enkephalins.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Differential response of neutral endopeptidase 24.11 ("enkephalinase"), and cholinergic and opioidergic markers to hypoglossal axotomy. 820 Oct 16