Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A periplasmic aminoendopeptidase from Escherichia coli has been purified to hemogeneity. It is a monomer of molecular weight 45000 and containing one -- SH group that is necessary for catalytic activity. The study of its substrate specificity indicated that the enzyme has both aminopeptidase and endopeptidase activity. The pH optimum for L-alanine p-nitroanilide hydrolysis is between 7 and 7.5 and that for 125I-labeled casein proteolysis between 7.3 and 7.6. The activation energy for the hydrolysis of L-anine p-nitroanilide was calculated to be 5.3 kcal X mol-1 (22.2 kJ X mol-1).
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PMID:Purification and properties of a periplasmic aminoendopeptidase from Escherichia coli. 0 Dec 71

Three homogeneous preparations of D-alanine carboxypeptidases I have been obtained from Escherichia coli strain H2143, termed enzymes IA, IB, and IC. Enzyme IA purified from the membrane after extraction with Triton X-100 appeared on sodium dodecyl sulfate gel electrophoresis to be a polypeptide doublet whose monomer molecular weights were about 32,000 and 34,000. In addition to D-alanine carboxypeptidase activity, it catalyzed a transpeptidase reaction with several substrates, bound [14C]penicillin G, had a weak penicillinase activity, but was devoid of endopeptidase activity. Enzyme IB obtained from the membrane after LiCl extraction and enzyme IC obtained from the supernatant solution were either identical or extremely similar. They were composed of a single polypeptide whose monomer molecular weight was about 41,000. In addition to carboxypeptidase activity, they catalyzed an endopeptidase reaction, had weak penicillinase activity, and had very poor transpeptidase activity, but did not bind [14C]penicillin G. Some data relating to the mechanism of catalysis by these enzymes are described. Their possible physiological role is discussed.
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PMID:Purification to homogeneity and properties of two D-alanine carboxypeptidases I From Escherichia coli. 0 91

An aminopeptidase was isolated from the culture filtrate of Clostridium histolyticum and purified to homogeneity. Absence of endopeptidase activity in the purified preparation was demonstrated. Gel filtration on a calibrated column indicates an apparent molecular weight of 340000 for the native enzyme. Gel electrophoresis of the denatured enzyme in the presence of dodecylsulfate in constant acrylamide concentration and in a concentration gradient, resulted in the appearance of a single component for which a molecular weight of 51000 and 59000 respectively, was calculated. From mobilities of crosslinked and denatured protein species a molecular weight of 56000 was obtained for the monomer. Specificity studies show that the enzyme cleaves all types of N-terminel amino acid residues including proline and hydroxyproline from small peptides and from polypeptides. The peptide bond formed between an N-terminal amino acid residue and proline is not cleaved by the enzyme. The combined action of aminopeptidase-P and clostridal aminopeptidase leads to complete hydrolysis of the proline-rich nonapeptide bradykinin. Low rates of hydrolysis was observed for charged residues, and amides of amino acids. Kinetic studies with five tripeptides of the general structure X-Gly-Gly, where X stands for Leu, Phe, Val, Ala, or Pro, show a decrease in Km with the increasing size of the hydrophobic side chain of X. The highest Kcat values are observed with proline and alanine. In the series Pro-Gly, Pro-Gly-Pro, Pro-Gly-Pro-Pro, the last peptide is the best substrate, indicating an active site complementary to at least four amino acid residues. The enzymatic activity is dependent on the presence of divalent cations, maximal activation being reached with Mn2+ and Co2+. The optimal pH for the Mn2+ and Co2+- activated enzyme is 8.6 and 8.2 respectively. The optimal temperature is 40 degrees C. Inhibition of the aminopeptidase was achieved with Zn2+, Cu2+ and p-mercuribenzoate, but not with diisopropylphosphofluoridate.
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PMID:An extracellular aminopeptidase from Clostridium histolyticum. 0 18

Seven strains of viridans streptococci of the species Streptococcus sanguis, S. mutans and S. mitis were investigated for autolysis. The effect of pH, salt concentration and temperature on the autolytic process was studied in Na2HPO4/NaH2PO4 buffer. Whole cells and walls of all strains autolysed most rapidly at pH values above 7. Autolysis of whole cells of S. sanguis and one strain of S. mitis (ATCC15909) was maximal in 0-05 TO 0-2 M buffer, while the two S. mutans strains and S. mitis ATCC15912 showed maximal autolysis in 0-5 and 1-0 M buffers. Cultures harvested in the stationary phase of growth possessed only slightly decreased autolytic activity compared with those from the exponential phase. Whole cells autolysed more rapidly at 37 degrees C Than at 45 degrees C and 10 degrees C. Autolysis of isolated walls of three strains of S. mitis (ATCC903, ATCC15909 and ATCC15912) was maximal at pH 7-0 AND 7-5 and in 1-0 M buffers. Streptococcus mitis ATCC15909 also showed maximal lysis in 0-01 M and 0-5 M buffers. An endopeptidase action of the autolytic system of S. mitis ATCC15912 was indicated by the progressive release of soluble amino groups during autolysis of the walls. No release of reducing groups was observed. Several free amino acids were released during autolysis of these walls, alanine, lysine and glutamic acid being in greatest quanitity.
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PMID:Autolysis in strains of viridans streptococci. 1 Mar 49

This study demonstrates, for the first time, the autolytic enzymes associated with mycobacterial cell walls. Based on the release of radioactivity and ninhydrin-reactive material from isolated cell walls, it was shown that maximum activity occurs during the late log phase of growth and at a buffer pH of about 8.0. Chemical analyses of autolytic digests of isolated cell walls indicated that at least three autolysins are active under the conditions used. These are N-glycolylmuramic acid-L-alanine amidase, an aminopeptidase that releases L-alanine, and an endopeptidase that solubilizes and L-alanyl-D-glutamic acid dippetide. No other endopeptidase, carboxypeptidase, or glycosidase activity was detected.
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PMID:Characterization of autolysins from Mycobacterium smegmatis. 1 9

A histochemical method for the demonstration of a brush border endopeptidase is described based on results of biochemical and histochemical experiments. The substrate of choice is Glut-Ala-Ala-Ala-MNA which displays a very good localization ability and suitable kinetic properties. Km estimated in rat kidney homogenate amounts to 2.35 X 10(-4) M. pH optimum of this endopeptidase associated with the brush border membrane is in the alkaline range. The activity is dependent on the buffer used. In phosphate and cacodylate buffers of pH 7.2 about 30% lower activity in rat kidney and about 25% lower activity in rat small intestine than in Tris-HCl buffer of the same pH was found. The most suitable diazonium salt for the detection "in situ" is Fast Blue B. It inhibits the endopeptidase activity of rat kidney by about 85% at pH 7.2 AND BY ABOUT 55% AT PH 6.0. The best results are obtained in cryostat sections adherent to semipermeable membranes treated with chloroform-acetone before the incubation. A microdensitometric evaluation of the reaction product is possible and results are in good agreement with those of the biochemical determination. When Suc-Ala-Ala-Ala-INA is used as substrate hexazonium-p-rosaniline is the most suitable coupling agent although it inhibits more than Fast Blue B. The reaction using acylated trialanyl naphthylamides as substrates runs in two steps. Endopeptidase sets free Ala-NA which is attacked by aminopeptidase M. Aminopeptidase M is not reaction rate or localization limiting factor because its activity in the brush border is very high and the enzyme is anchored to the cell membrane very closely to endopeptidase. In homogenates of rat kidney and jejunal mucosa the endopeptidase activity was inhibted by EDTA (2X10(-3) M) by 75% in the kidney and by 68% in the jejunum, by DFP (10(-3) M) by 41% in the kidney and by 35% in the intestine, by Mn2+ (5X10(-3) M) by 25% in the kidney and by 30% in the intestine. No inhibition was exerted by E 600. In sections the results were similar. 1,10-phenanthroline (10(-2) M) caused a substantial inhibition. Endopeptidase activity was detected in the brush border of cells of proximal convuluted tubules of the kidney and in the brush border of differentiated enterocytes of the small intestine. In the same species enterocytes display a lower activity than kidney tubular cells. There are species differences in the distribution pattern of endopeptidase in the kidney. In the rabbit and man the positive reaction occurs in the whole cortex. It is distributed unevenly, however. In the rat the tubules of the inner cortex display a very high activity. In the outer cortex straight portions react strongly. In the rabbit kidney cells of the parietal layer of Bowman's capsule display a weak reaction as well. No sex differences were found in the distribution pattern of endopeptidase in the rat kidney. In the intestine of all species examined a proximo-distal gradient was found...
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PMID:The histochemical demonstration of brush border endopeptidase. 9 94

1. The synthetic peptide, 2,4-dinitrophenyl-L-Pro-L-Leu-Gly-L-Ile-L-Ala-Gly-L-Arg-amide (DNP-peptide) was tested as a potential substrate for uterine collagenase. Rat uteri were homogenized and the insoluble fraction was extracted at 60 degrees C to obtain collagenase. The extracts were chromatographed on Sephadex G-150 to yield two peaks of DNP-peptide hydrolyzing activity. Peak I was completely inhibited by EDTA and had a molecular weight greater than 100 000. Peak II was inhibited about 90% by EDTA and had an apparent molecular weight of about 70 000. 2. Peak II coincided closely, but not exactly, with the peak of collagenase activity. It differed from collagenase in heat stability, binding properties on CM-Sephadex and failure to display latency. 3. Peak II represents a new endopeptidase activity. It has a pH optimum of 7 and it cleaves the DNP-peptide at the Gly-Ile and, possibly, the Leu-Gly bond. 4. The DNP-peptide is not a satisfactory substrate for the assay of impure collagenase preparations nor does it inhibit the action of collagenase on collagen substrate when added in 30-fold molar excess.
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PMID:Separation of collagenase and a metal-dependent endopeptidase of rat uterus that hydrolyzes a heptapeptide related to collagen. 22 33

Proteolytic removal of the pre-segment from growing nascent chains of pre-human placental lactogen (hPL) occurred during in vitro translation of placental mRNA if crude membranes derived from ascites lysates, dog pancreas, or rat liver rough endoplasmic reticulum were added to the translation mixtures. The cotranslational proteolytic event was inhibited by the peptide protease inhibitor, chymostatin, but not by leupeptin, antipain, or elastatinal. The proteases involved in cleavage were solubilized with detergent and converted completed pre-hPL to hPL (post-translational processing). Direct assay of the solubilized membranes, with synthetic fluorogenic aminocoumarin peptide substrates, revealed no significant tryptic or elastase-like activity, but activity against a chymotrypsin substrate [(succinyl-Ala-Ala-Phe)-7-amino-4-methyl-coumarin] was found. This activity was dependent upon both an endopeptidase and an aminopeptidase. Although bestatin inhibited the aminopeptidase activity, it had no effect on the endopeptidase or on post-translational cleavage. Although this endopeptidase cleaved on the COOH side of an alanine residue, it was not inhibited by elastatinal. However, it was inhibited by high levels of chymostatin and by some serine protease inhibitors.
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PMID:Characterization of an endopeptidase involved in pre-protein processing. 29 60

Stimulation of [(3)H]thymidine incorporation of thymocytes and splenocytes from guinea pigs by various bacterial cell walls and their peptidoglycans, by enzymatic digests, and by synthetic muramyl dipeptides was studied as an indication of mitogenic activity. Cell wall and peptidoglycan preparations, isolated from 19 strains belonging to 18 different species, definitely increased [(3)H]thymidine incorporation of thymocytes as well as splenocytes, regardless of mycolic acid contents as a non-peptidoglycan component. Both the cell walls from Nocardia corynebacteriodes (containing mycolic acids) and those from Streptomyces gardneri (lacking mycolic acids) showed far stronger mitogenic activities on splenocytes than other cell walls (stimulation index, 25 to 30). Furthermore, water-soluble enzymatic digests, notably the endopeptidase digests, which generally were greater in degree of polymerization of peptidoglycan subunits than the glycosidase digests obtained from representative cell walls, were found to have as distinct a stimulating activity on splenocytes as the original cell walls. In contrast, solubilization of the cell walls by enzymes, irrespective of endopeptidases or glycosidases, was accompanied by disappearance of the mitogenic activity on thymocytes. On the other hand, studies with synthetic 6-O-acyl-MurNAc-l-Ala-d-isoGln preparations (6-O-acyl-MDPs) revealed that 6-O-stearoyl-MDP and 6-O-(2-tetradecylhexadecanoyl)-MDP, unlike MDP, had distinct mitogenic activity on thymocytes, whereas their activity on splenocytes was rather weaker than MDP itself. The findings presented here suggest that MDP is the minimal structure for the mitogenic activities of bacterial cell walls on guinea pig splenocytes, but that MDP, though distinctively active by itself, requires a polymerized form to exert effectively its inherent stimulating activities on splenocytes. On the other hand, on thymocytes, MDP, unless it takes a particular form or has appropriate additive groups, cannot exert its mitogenic activities.
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PMID:Mitogenic effects of bacterial cell walls, their fragments, and related synthetic compounds on thymocytes and splenocytes of guinea pigs. 31 32

Mutants of Escherichia coli with much decreased activity of D-alanine carboxypeptidase (peptidyl-D alanine hydrolase, EC 3.4.12.11) were found among E. coli K12 extensively mutagenized with nitrosoguanidine treatment by assaying individual colonies for the enzyme activity. One such mutant with only 10-12% residual activity was characterized extensively. The soluble carboxypeptidase activity (corresponding to D-alanine carboxypeptidase IC of Tamura T., Imae, Y. & Strominger, J.L. [(1976) J. Biol. Chem. 251, 414-423] was deleted. This enzyme activity in the particulate fraction was markedly reduced but transpeptidase activity was normal. However, penicillin-binding component IV was deleted from the particulate fraction. Both the physiology and penicillin sensitivity of the organism were relatively normal, except that mutant cells were markedly more stable to penicillin-induced lysis, suggesting the possibility that carboxypeptidase IC really functions as an endopeptidase. The possible relationship of the deleted carboxypeptidase activity and the deleted penicillin binding component are discussed.
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PMID:Simultaneous deletion of D-alanine carboxypeptidase IB-C and penicillin-binding component IV in a mutant of Escherichia coli K12. 33 23


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