Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O95477 (membrane-bound)
 29,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The membrane-bound form of aminopeptidase P (aminoacylprolyl-peptide hydrolase) (EC 3.4.11.9) was purified to apparent homogeneity from bovine lung microsomes. The enzyme was solubilized using phosphatidylinositol-specific phospholipase C (Bacillus thuringiensis), indicating that bovine lung amino-peptidase P is attached to membranes via a glycosylphosphatidylinositol anchor. The enzyme was purified 1900-fold with a yield of 25% by chromatography on decyl-agarose, omega-aminodecyl-agarose, a second decylagarose column, DEAE-Sephacel, and an ultrafiltration step. Native gradient polyacrylamide gel electrophoresis revealed a single stained protein band whose position in the gel corresponded to cleavage of the Arg1-Pro2 bond of bradykinin. The Mr was 360,000 by gel permeation chromatography and 95,000 by reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The substrate specificity of aminopeptidase P was determined using approximately 50 peptides with proline in the second position. The enzyme could hydrolyze lower NH2-terminal homologs of bradykinin, including Arg-Pro-Pro, which was used as the routine substrate in a rapid fluorescence assay performed in the absence of added Mn2+. Some peptides having NH2-terminal amino acids other than arginine were also cleaved. Aminopeptidase P appeared to favor peptides that had 2 proline residues or proline analogs in positions 2 and 3 of the substrate. In general, tripeptides having a single proline residue in position 2 were poor substrates. Aminopeptidase P was inhibited by a series of peptides, 3-8 residues long, having an NH2-terminal Pro-Pro sequence. The enzyme was also inhibited by metal-chelating agents, 2-mercaptoethanol (4 mM), p-chloromercuribenzenesulfonic acid, and NaCl at concentrations greater than or equal to 0.25 M. The purified enzyme had a pH optimum of 6.5-7.0 and was most stable in the basic pH range. A role for membrane-bound aminopeptidase P in the pulmonary inactivation of circulating bradykinin is proposed.
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PMID:Membrane-bound aminopeptidase P from bovine lung. Its purification, properties, and degradation of bradykinin. 153 67

The substrate specificity of recombinant E. coli aminopeptidase P (aminoacylprolylpeptide hydrolase) (EC 3.4.11.9) was studied using about 150 synthetic peptides. E. coli aminopeptidase P released the N-terminal amino acid from most peptides containing a penultimate proline, although the relative rates of hydrolysis varied over two orders of magnitude. Dipeptides (X-Pro) were hydrolyzed relatively slowly. Detailed kinetic analysis using peptides of different lengths suggested that the enzyme has at least four subsites for interaction with substrates, namely S1, S'1, S'2, and S'3. S1 and S'1 have high stereo-specificity Various Pro-X dipeptides where X is a hydrophobic amino acid were competitive inhibitors of the enzyme. The substrate specificity of E. coli aminopeptidase P was compared to that of purified bovine lung and rat lung membrane-bound aminopeptidase P. The mammalian enzymes had much more restricted substrate specificities. The differences appeared to be due primarily to differences in the S'2 subsite. The E. coli enzyme could accommodate bulky amino acid side chains in the S'2 subsite, whereas the mammalian membrane-bound enzymes could not.
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PMID:Substrate specificity of aminopeptidase P from Escherichia coli: comparison with membrane-bound forms from rat and bovine lung. 818 18

Complementary DNA clones encoding human membrane-bound aminopeptidase P (AmP) were isolated by reverse transcription-polymerase chain reaction (RT-PCR) of human kidney and lung poly (A)+ RNA. Comparison of the human AmP sequence to that of the pig shows significant evolutionary divergence with only 83% amino acid sequence identity between the two species. Northern hybridization analysis and RT-PCR suggests that the soluble and membrane-bound forms of human AmP are products of two distinct genes or, through alternative splicing, have different C-terminal sequences.
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PMID:Cloning and tissue distribution of human membrane-bound aminopeptidase P. 937 90

Membrane-bound aminopeptidase P (AP-P) participates in the degradation of bradykinin in several vascular beds. We have developed an inhibitor of AP-P called apstatin (1) (N-[(2S, 3R)-3-amino-2-hydroxy-4-phenyl-butanoyl]-L-prolyl-L-prolyl-L-al aninam ide); IC50,human = 2.9 microM. In the rat, apstatin can potentiate the vasodilatory effect of bradykinin, reduce blood pressure in an aortic-coarctation model of hypertension, and reduce cardiac damage and arrhythmias induced by ischemia/reperfusion. In this study, we have determined structure-activity relationships for apstatin analogues as well as for other chemical classes of inhibitors using AP-P isozymes from different sources. The most potent inhibitor was one in which the N-terminal residue of apstatin was replaced with a (2S,3R)-3-amino-2-hydroxy-5-methyl-hexanoyl residue (6, IC50,human = 0.23 microM). The (2R,3S)-analogue of 6 was equipotent with 6 while the (2S,3S)- and (2R,3R)-analogues were considerably less potent. Apstatin analogues lacking the L-alanine or having hydroxyproline in place of the proline in the second position had reduced affinity. Certain thiol-, carboxylalkyl-, and hydroxamate-containing compounds were inhibitory in the low micromolar range. Human cytosolic AP-P isozymes and Escherichia coli AP-P exhibited different inhibitor profiles than mammalian membrane-bound AP-P isozymes. The effects of the compounds on X-Pro dipeptidase (prolidase) and leucyl aminopeptidase are also presented.
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PMID:Apstatin analogue inhibitors of aminopeptidase P, a bradykinin-degrading enzyme. 1039 80