Cloning, sequencing and further characterization of acylpeptide hydrolase from porcine intestinal mucosa.
Acylpeptide hydrolase was purified to homogeneity from porcine intestinal mucosa using a seven-step procedure including ammonium sulfate precipitation, gel filtration as well as anion exchange and affinity chromatography. The specific activity of the enzyme reached 105000 nmol/mg protein per min and the purification was as high as 5500-fold. This tetrameric enzyme is composed of four apparently identical subunits, the molecular mass of which was estimated to be 75 kDa, based on the results of amino acid analysis and gel electrophoresis performed under denaturing conditions. It is likely that the NH(2)-terminal residue may be acetylated, while serine was found to be the COOH-terminal residue. The hydrolytic activity of the enzyme toward N-acetyl-L-alanine p-nitroanilide at the optimum pH value was increased twofold in the presence of the chloride anion. The K(m) value calculated from the kinetics of the hydrolysis of acetylalanyl peptides was found to be 0.7+/-0.1 mM, whereas the V(max) values decreased from 200 to 50 nmol/min per microgram of enzyme, depending on the peptidic chain lengths. The V(max) value of the synthetic substrate (250 nmol/min per microgram of enzyme) was 25-500% higher than those of the acetylalanyl peptides, depending on the peptide chain length, although the enzyme affinity was slightly lower (1.8 mM as compared with 0.7 mM). In line with data on other animal species and on various tissues, the enzyme seemed likely to be a serine protease, since it was readily inhibited by diisopropyl fluorophosphate and diethyl pyrocarbonate. A 2377-nucleotide long cDNA coding for the enzyme was isolated from pig small intestine. The deduced amino acid sequence consisted of 731 residues and showed a single different amino acid with that of the porcine liver APH, except the N-terminal amino acid which is still probably lacking.
Laboratoire de Biochimie et Biologie de la Nutrition, CNRS-ESA 6033, Faculté des Sciences et Techniques de St-Jérôme, 13397, Marseille Cédex 20, France.
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V
Raphel
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T
Giardina
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L
Guevel
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J
Perrier
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L
Dupuis
X J
XJ
Guo
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A
Puigserver
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D013552:Swine
D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D010447:Peptide Hydrolases; C038220:acylaminoacyl-peptidase