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)

Ferret tracheal segments were infected with human influenza virus A/Taiwan/86 (H1N1) in vitro. After 4 days, the smooth muscle contractile responses to acetylcholine and to substance P were measured. The response to substance P was markedly accentuated, with a threefold increase in force of contraction at a substance P concentration of 10(-5) M, the highest concentration tested. In contrast, the response to acetylcholine was not affected by viral infection. Histological examination of tissues revealed extensive epithelial desquamation. Activity of enkephalinase (neutral metallo-endopeptidase, EC.3.4.24.11), an enzyme that degrades substance P, was decreased by 50% in infected tissues. Inhibiting enkephalinase activity by pretreating with thiorphan (10(-5) M) increased the response to substance P to the same final level in both infected and control tissues. Inhibiting other substance P-degrading enzymes including kininase II (angiotensin-converting enzyme), serine proteases, and aminopeptidases did not affect the response to substance P. Inhibiting cyclooxygenase and lipoxygenase activity using indomethacin and BW 755c did not affect hyperresponsiveness to substance P. Pretreating tissues with antagonists of alpha-adrenoceptors, beta-adrenoceptors, and H1 histamine receptors (phentolamine 10(-5) M, propranolol 5 X 10(-6) M, and pyrilamine 10(-5) M, respectively) had no effect on substance P-induced contraction. These results demonstrate that infection of ferret airway tissues with influenza virus increases the contractile response of airway smooth muscle to substance P. This effect is caused by decreased enkephalinase activity in infected tissues.
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PMID:Influenza infection causes airway hyperresponsiveness by decreasing enkephalinase. 304 36

An endopeptidase was isolated from bovine adrenomedullary granules by fast protein liquid chromatography, including two ion exchange, one hydrophobic interaction, and one gel filtration step. The enzyme assay was based on the HPLC detection of the degradation of the dodecapeptide BAM 12P from the sequence of proenkephalin. After a 1200-fold purification, the enzyme fraction was homogeneous on polyacrylamide gel electrophoresis. The apparent molecular weight of the monomeric protein was 68,000 and its pH optimum was 5.6, in agreement with the internal pH of the granules. The specificity of the protease was determined initially by analysis of the degradation fragments of BAM 12P which showed that cleavage occurred at the double but not at the single Arg site of BAM 12P. The cleavage pattern of other substrates showed that the enzyme also recognized other pairs of basic amino acids. The behavior of the enzyme toward specific inhibitors showed that it was an acid thiol protease different from serine proteases and from lysosomal cathepsin B. The endopeptidase may act as a maturation enzyme in vivo.
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PMID:Purification of an endopeptidase from bovine adrenal medulla granules which cleaves in vitro at paired but not at single basic residues. 305 95

Subunit III (BSIII) of the bovine ternary complex of procarboxypeptidase A-S6 (PCPA-S6), a defective serine endopeptidase-like protein, actively synthesized by the pancreas of some ruminant species, is highly homologous to human protease E (HPE). Both proteins possess the same atypical disulfide bridge in position 98-99b. They are structurally related to porcine elastase 1 and human elastase 2 (about 56% identity). However, in contrast to those two enzymes which have an overall positive net charge, BSIII and HPE are negatively charged. Three-dimensional models of BSIII and HPE have been constructed from the crystallographic structure of porcine pancreatic elastase 1. The inhibitor-binding site for TFAI in these three proteins seems to be very similar; the atypical disulfide bridge does not seem to be involved in this binding site. The specific structural features of BSIII and HPE strongly support the assumption that BSIII is a truncated protease E and that both proteins belong to a separate serine endopeptidase family.
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PMID:Subunit III of ruminant procarboxypeptidase A-S6 complexes and pancreatic proteases E. A new family of pancreatic serine endopeptidases? 316 5

A serine endopeptidase was characterized as a major inactivating enzyme for endogenous cholecystokinin (CCK) in brain. CCK-8 released by depolarization of slices of rat cerebral cortex, as measured by its immunoreactivity (CCK-ir), undergoes extensive degradation (approximately 85% of the amount released) before reaching the incubation medium. However, recovery of CCK-ir is enhanced up to 3-fold in the presence of serine-alkylating reagents (i.e., phenylmethylsulfonyl fluoride) as well as selected active site-directed inactivators (i.e., peptide chloromethyl ketones) or transition-state inhibitors (i.e., peptide boronic acids) of serine peptidases. Among these compounds, elastase inhibitors were the most potent protecting agents, whereas trypsin or chymotrypsin inhibitors were ineffective. HPLC analysis of endogenous CCK-ir recovered in media of depolarized slices indicated that endogenous CCK-5 [CCK-(29-33)-pentapeptide] was the most abundant fragment and that its formation was strongly decreased in the presence of an elastase inhibitor. HPLC analysis of fragments formed upon incubation of exogenous CCK-8 [CCK-(26-33)-octapeptide] with brain slices showed CCK-5, Gly-Trp-Met, and Trp-Met to be major metabolites of CCK-8 whose formation was prevented or at least diminished in the presence of the elastase inhibitor. It is concluded that there is an elastase-like serine endopeptidase in brain that cleaves the two peptide bonds of CCK-8 where the carboxyl group is donated by a methionine residue and constitutes a major inactivation ectoenzyme for the neuropeptide.
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PMID:A serine peptidase responsible for the inactivation of endogenous cholecystokinin in brain. 318 27

Proteinase K, the extracellular serine endopeptidase (E.C.3.4.21.14) from the fungus Tritirachium album limber, is homologous to the bacterial subtilisin proteases. The binding geometry of the synthetic inhibitor carbobenzoxy-Ala-Phechloromethyl ketone to the active site of proteinase K was first determined from a Fourier synthesis based on synchrotron X-ray diffraction data between 1.8 A and 5.0 A resolution. The protein inhibitor complex was refined by restrained least-squares minimization with the data between 10.0 and 1.8 A. The final R factor was 19.1%, and the model contained 2,018 protein atoms, 28 inhibitor atoms, 125 water molecules, and two Ca2+ ions. The peptide portion of the inhibitor is bound to the active center of proteinase K by means of a three-stranded antiparallel pleated sheet, with the side chain of the phenylalanine located in the P1 site. Model building studies, with lysine replacing phenylalanine in the inhibitor, explain the relatively unspecific catalytic activity of the enzyme.
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PMID:X-ray and model-building studies on the specificity of the active site of proteinase K. 323 15

The structure of the serine endopeptidase proteinase K (279 amino acid residues; 28,790 daltons) has been refined by restrained least-squares methods to a conventional R value of 16.7% employing synchrotron film data of 30,812 reflections greater than 3 sigma in the 5.0 to 1.5 A resolution range. During refinement, the molecular structure was restrained to known stereochemistry, with root-mean-square (r.m.s.) deviation of 0.015 A from ideal bond lengths. The average atomic temperature factor, B, is 11.1 A2 for all atoms. The final model comprises 2020 protein atoms and 174 solvent molecules (which were given unit occupancies). Four corrections to the amino acid sequence were made, which were confirmed later by sequence analysis of the proteinase K gene: a deletion of one glycine in position 80; a change of sequence in position 207-208 and insertions of the dipeptide 210-211 and of residue 270. The r.m.s. deviation in the alpha-C atomic positions between the final refined model and the initial model built on the basis of a 3.3 A mini-map is 1.72 A for 227 out of 266 residues, which were originally traced in the mini-map without sequence information. The positions of the remaining 39 residues deviate by more than 8 A from the original ones and are located in regions where extensive revision of the structural model was necessary.
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PMID:Synchrotron X-ray data collection and restrained least-squares refinement of the crystal structure of proteinase K at 1.5 A resolution. 327 Nov 5

The sinus gland is a major neurosecretory structure in Crustacea. Five peptides, labeled C, D, E, F, and I, isolated from the sinus gland of the land crab have been hypothesized to arise from the incomplete proteolysis at two internal sites on a single biosynthetic intermediate peptide "H", based on amino acid composition additivities and pulse-chase radiolabeling studies. The presence of only a single major precursor for the sinus gland peptides implies that peptide H may be synthesized on a common precursor with crustacean hyperglycemic hormone forms, "J" and "L," and a peptide, "K," similar to peptides with molt inhibiting activity. Here I report amino acid sequences of these peptides. The amino terminal sequence of the parent peptide, H, (and the homologous fragments) proved refractory to Edman degradation. Data from amino acid analysis and carboxypeptidase digestion of the naturally occurring fragments and of fragments produced by endopeptidase digestion were used together with Edman degradation to obtain the sequences. Amino acid analysis of fragments of the naturally occurring "overlap" peptides (those produced by internal cleavage at one site on H) was used to obtain the sequences across the cleavage sites. The amino acid sequence of the land crab peptide H is Arg-Ser-Ala-Asp-Gly-Phe-Gly-Arg-Met-Glu-Ser-Leu-Leu-Thr-Ser-Leu-Arg-Gly- Ser-Ala-Glu- Ser-Pro-Ala-Ala-Leu-Gly-Glu-Ala-Ser-Ala-Ala-His-Pro-Leu-Glu. In vivo cleavage at one site involves excision of arginine from the sequence Leu-Arg-Gly, whereas cleavage at the other site involves excision of serine from the sequence Glu-Ser-Leu. Proteolysis at the latter sequence has not been previously reported in intact secretory granules. The aspartate at position 4 is possibly covalently modified.
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PMID:Amino acid sequences of neuropeptides in the sinus gland of the land crab Cardisoma carnifex: a novel neuropeptide proteolysis site. 329 49

By using a sensitive fluorometric method with Val-Leu-Gly-Arg-3-amino-9-ethylcarbazole (VLGR-AEC) as a substrate, two endopeptidase activities were identified in two fractions of Sephacryl S-200 gel filtration from soluble P. berghei and P. chabaudi extracts. Controls with normal mouse erythrocytes, with leukocytes, and with reticulocyte enriched blood and different washing procedures during the preparation of soluble P. berghei extracts showed that the MW greater than 200 kDa fraction was a contaminant from erythrocytes and exhibited an optimal pH activity of 8.2. In contrast, the fraction 130 kDa was related to P. berghei and P. chabaudi and exhibited an optimal pH activity of 7.4. The two enzyme activities were compared with eight different substrates. The parasite endopeptidase showed a strong activity with Val-Leu-Gly-Lys-AEC (VLGK-AEC) and Ser-Gly-Lys-AEC (SGK-AEC) as substrates; in contrast, the mouse host endopeptidase poorly cleaved the VLGK-AEC and did not cleave SGK-AEC. Presence of the hydrophobic benzyl group on serine reduced the hydrolizing properties of P. berghei endopeptidase: the reverse was observed with host endopeptidase. The hydrolysis of the N-polyhydroxyalcanoyl-VLGK-AEC substrate by the parasite neutral endopeptidase strongly increased with the schizogonic stage, as shown with synchronized P. chabaudi in mice. By its physiological pH and specificity the release of this enzyme in mouse plasma during the infection could be of interest in a peptidyl-drug strategy.
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PMID:Plasmodium berghei and Plasmodium chabaudi: a neutral endopeptidase in parasite extracts and plasma of infected animals. 330 90

A multicatalytic endopeptidase (ME) with three distinct activities, chymotrypsin-like, cucumisin-like, and trypsin-like, occurred in all rat tissues examined with highest activities in kidney, testes, liver, and spleen; they were assayed with benzyloxycarbonyl-Gly-Gly-Leu-p-nitroanilide (Z-Gly-Gly-Leu-pNA), benzyloxycarbonyl-Leu-Leu-Glu-2-naphthylamide (Z-Leu-Leu-Glu-2NA), and benzyloxycarbonyl-Gly-Gly-Arg-2-naphthylamide (Z-Gly-Gly-Arg-2NA), respectively. All three activities were recovered from a single protein band on a polyacrylamide gel after electrophoresis of purified human kidney ME. The native enzyme had a Mr of 650,000, and it consisted of about 5,135 amino acid residues. After denaturation and electrophoresis on sodium dodecyl sulfate (SDS)-polyacrylamide gels kidney ME dissociated into several low Mr components ranging from 23,000 to 33,000. Kidney ME had a pH optimum of 7.6-8.1 with Z-Gly-Gly-Leu-pNA, 7.3 with Z-Leu-Leu-Glu-2NA, and 9.8 with Z-Gly-Gly-Arg-2NA. SDS enhanced chymotrypsin- and cucumisin-like activities by two to three times whereas trypsin-like activity was not enhanced. The specificity constant (kappa cat/Km) of human kidney ME for Z-Gly-Gly-Leu-pNA was 6.7 X 10(3) M-1 S-1; Z-Gly-Gly-Leu-2NA was not hydrolyzed. The specificity constant for Z-Leu-Leu-Glu-2NA was similar to, and for Z-Gly-Gly-Arg-2NA was one half of that for Z-Gly-Gly-Leu-pNA. ME cleaves only the Phe5-Ser6 bond of bradykinin (BK); however, all three ME activities were inhibited by BK. Strong inhibition of ME by albumin suggests that ME is involved in cleavage of larger polypeptides. Antipain and leupeptin almost completely inactivated the trypsin-like activity whereas they had no significant effect on the other two activities. ME is not a metal-loenzyme nor is the serine residue essential for its activities; however, thiol groups are involved. Na+ and K+ inhibited all ME activities. Trypsin-like activity was more sensitive to divalent cations than the other two.
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PMID:A multicatalytic high-molecular-weight neutral endopeptidase from human kidney. 331 Sep 3

The nature of the endoproteolytic activity involved in the post-translational processing of proinsulin has been investigated in rat insulinoma tissue. 125I-proinsulin was converted by lysed insulin-secretory granules into insulin via an intermediate form identified as des-dibasic-proinsulin. This activity co-localized with immunoreactive (endogenous) insulin and carboxypeptidase H upon subcellular fractionation of the tissue, indicating a secretory-granular location. Under optimized conditions, conversion was quantitative. Inhibitor studies demonstrated that processing occurred by a reaction sequence involving cleavage on the C-terminal side of the pairs of basic amino acids, with subsequent removal of the newly exposed basic residues by carboxypeptidase H. Endoproteolytic activity was abolished by EDTA and CDTA (1,2-cyclohexanediaminetetra-acetic acid), but not by 1,10-phenanthroline or by group-specific inhibitors of serine, thiol or acidic proteinases. Inhibition by EDTA and CDTA could be reversed by both Ca2+ and Zn2+, although the former appeared to be the ion of physiological importance. Addition of Ca2+ in the absence of chelators stimulated endoproteinase activity, with a maximal effect at 5 mM, a concentration consistent with the intragranular environment. Similarly the pH optimum of 5.5 coincides with the prevailing intragranular pH. Together these properties suggest that the Ca2+-dependent endopeptidase described here is involved in vivo in the proteolytic processing of proinsulin.
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PMID:Proteolytic conversion of proinsulin into insulin. Identification of a Ca2+-dependent acidic endopeptidase in isolated insulin-secretory granules. 331 7


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