Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Large quantities of the low-molecular-weight natriuretic material (F4), which appears after the salts when fractionated on G-25 Sephadex column, were obtained from the urine of normal man on a normal diet. The natriuretic substance in F4 was (1) untrafiltrable through a membrane with a claimed molecular-weight cut-off of 500 daltons (Amicon UMO5); (2) soluble in more polar organic solvents; (3) totally soluble in 95% acetone when specific activity was doubled; (4) relatively resistant to heating at 100 degrees C for 1 hour at a pH of 10, and to heating at 110 degrees C in 6 N hydrochloric acid for up to 90 hours under anaerobic conditions, and treatment with nitrous acid; it was less resistant to these procedures when extracted into 95% acetone; (5) not destroyed by trypsin, chymotrypsin, pronase, pepsin, leucine aminopeptidase, and subtilysin, nor was it destroyed by pepsin, leucine aminopeptidase, subtilysin, carboxypeptidase A and B, and aminopeptidase M, or by monoamine oxidase, aryl sulphatase, and beta-glucuronidase when extracted into 95% acetone. The natriuretic substance in the 95% acetone-soluble F4 was totally destroyed by incubation with prolidase. The least amount of 95% acetone-soluble F4 required to produce a significant natriuresis in the bioassay rat was that derived from a 7-min sample of urine. The maximal response was obtained from a 30-min sample of urine. Continuous i.v. infusion of the 95% acetone-soluble F4 for 40 min produced a sustained natriuresis, whereas a greater amount injected as a bolus produced an effect which was not sustained beyond 20 min.
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PMID:Further observations on a low-molecular-weight natriuretic substance in the urine of normal man. 4 87

During the storage of secretin in acid and neutral aqueous solutions, five degradation peptides (A1, A2, A3, A4, A5) and one degradation peptide (N1) were produced, respectively. They were isolated in pure form by HPLC, and the intramolecular structures were studied by a combination of amino acid analysis, enzymatic digestions, HPLC, and Fab-mass spectroscopy. Although the degradation peptides are composed of the same amino acids as secretin after acid hydrolysis (except A1 and A4 which are cleavage products S16-27 and S4-27, respectively), reversed-phase HPLC analysis of their digestive fragments with trypsin and alpha-chymotrypsin are different from those of secretin. By Fab-mass spectroscopy, the m/z values for the S1-6 fragments obtained from secretin, A2, and A3 were 663, 663, and 645, respectively. When S1-6 from A2 was treated with aminopeptidase M, a fragment obtained was identical with the synthetic beta-aspartyl3 S3-6, as determined by HPLC. The A2 and N1 peptides are completely the same based on various chemical analyses. The A3 peptide can also be rapidly degraded to secretin and beta-aspartyl3 secretin. Consequently, A1 and A4 are concluded to be the cleavage peptides of secretin, S16-27 and S4-27, respectively, A2 and N1 are concluded to be beta-aspartyl3 secretin, and A3 is concluded to be aspartoyl3 secretin.
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PMID:Degradation peptides of secretin after storage in acid and neutral aqueous solutions. 231 77

The amino acid residues of spinach CF1 subunit delta are identified which are accessible and thus exposed within the quaternary structure of the ATP-synthase complex on the thylakoid membrane. Two types of antibodies in the monospecific polyclonal antiserum 306 against CF1 delta, described in the previous publication [Z. Naturforsch. 44c, 153-160 (1989)], were separated by virtue of their different affinity to thylakoid membranes and used for specific analysis of the products of proteolytic digestion of delta in situ. Polypeptide delta in situ, i.e. within the CF0 CF1 complex on the membrane, is not susceptible to digestion by aminopeptidase M and trypsin, but is shortened by about 1 kDa by carboxypeptidase Y and digested at residues Glu173 and Glu179 by the Staphylococcus aureus protease V8. The epitope on delta reacting with the agglutinating antibodies from serum 306 is lost after these proteolytical treatments and therefore situated on residues Met180-Val187. Since trypsin destroys this epitope only after prolonged incubation and with at least 50 micrograms trypsin/mg Chl, residue Lys169 of delta probably is inaccessible in situ. We conclude that the C-terminal amphipathic alpha-helix of spinach CF1 subunit delta is exposed on the thylakoid membrane, with the hydrophilic face directed to the outside, and that CF1 delta starts to be shielded within the quaternary structure of the CF0 CF1 complex between Glu173 and Lys169. The hydrophobic face of the c-terminal helix may be part of the binding surface towards CF0. Antibodies from serum 306 inhibit the PMS mediated cyclic photophosphorylation by reacting with C-terminal residues of delta.
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PMID:Localization and orientation of subunit delta of spinach chloroplast ATP-synthase within the CF0 CF1 complex. 2. Identification of C-terminal residues of delta, exposed on the thylakoid membrane. 247 16

A detailed investigation is reported about the biodegradation of poly[Lys(DL-Alam)], m approximately 3, (AK) the common inside area of a branched polypeptide model system developed by our group over the last decade. Enzymatic hydrolysis was carried out by the exopeptidase aminopeptidase M, or the endopeptidase trypsin, or their mixture. Ion-exchange column chromatography, paper electrophoresis and thin-layer chromatography were utilised to achieve separation of metabolites. Breakdown products were identified by the aid of synthetic oligopeptides representing the potential fragments (DL-Ala2, DL-Ala3, Lys(DL-Alam), m = 1-3). The kinetics and the degree of enzymatic degradation were determined. The ratio of peptide/amino acid amounts in the hydrolysate was found to be 1.07 after 24 h treatment with aminopeptidase M, 3.0 with trypsin and 1.3 with aminopeptidase - trypsin mixture. The overall results indicated that the proteolysis of AK by an aminopeptidase M and trypsin mixture proceeds stepwise at multiple sites on the polypeptide chain. The degradation is significantly retarded as compared to that of alpha- or epsilon-polylysine. A mechanism of degradation is suggested based on the experimental results.
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PMID:Biodegradability of synthetic branched polypeptide with poly(L-lysine) backbone. 257 93

Purified bovine beta-casein was digested in vitro with varying mixtures of purified proteinases and peptidases including trypsin, chymotrypsin, dipeptidyl peptidase IV (DP IV), aminopeptidase M and prolidase. In digestion mixtures without DP IV the yield of free amino acids was considerably lower than in the corresponding assays with this peptidase. Especially, the release of proline increases drastically from almost zero to the theoretical amount in the presence of DP IV. Quantitative results indicated that the specificities of the two microvillar peptidases (aminopeptidase M and DP IV) optimally complemented each other. This effect elucidates the hitherto obscure physiological role of intestinal DP IV. A similar effect may also apply to other caseins and nutritional proteins.
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PMID:Complementary action of dipeptidyl peptidase IV and aminopeptidase M in the digestion of beta-casein. 287 57

Monoclonal antibodies were used to define cell surface antigens which are present on rat hepatocytes but are absent from hepatoma cells. One monoclonal antibody, referred to as Be 9.2, recognizes a major component of purified rat liver plasma membranes with a Mr of 110 000. This antigen (gp110) was not found in the transplantable Morris hepatoma 9121 and 7777 nor on two cultured hepatoma cell lines. Isoelectric focussing showed that gp110 is a very acidic membrane component with an isoelectric point of 3.6 to 3.8. Treatment with neuraminidase reduced the Mr to 95 000. Gp110 while bound to the membrane was resistant to trypsin, but sensitive to papain. The tissue distribution of gp110 was examined by indirect immunofluorescence in frozen sections. The antigen was found on the bile canalicular domain of hepatocytes, the microvillous zone of enterocytes of the small intestinal villi, the luminal plasma membrane of acinar cells in the submaxillary and extraorbital gland and of epithelial cells of the vesicular gland. Gp110 could not be detected in the stomach, pancreas, large intestine, kidney, thymus, spleen, heart, lung, muscle cells and fibers and in the brain. Identical results were obtained by the use of an antiserum raised against purified gp110. They confirm the transformation-sensitive character of this glycoprotein. A possible identity with dipeptidyl peptidase IV and aminopeptidase M, which have similar molecular weights and are also present in rat liver on the bile canalicular domains, could be excluded. The results suggest that the loss of gp110 might be regarded as a marker for transformation or dedifferentiation of hepatocytes.
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PMID:Identification of a transformation-sensitive 110-kDa plasma membrane glycoprotein of rat hepatocytes. 300 50

The stability of recombinant human superoxide dismutase (r-hSOD) in buffer solutions was studied in solutions at various pH and temperatures. Additionally, we studied the effects of incubation with proteases, serum and two types of hypothermic perfusates. R-hSOD was stable in the pH range of 6-11 and at temperatures up to 80 degrees C for 30 min. R-hSOD activity was not affected by incubation with trypsin, aminopeptidase M or serum for 2 h. R-hSOD activity determined at various temperatures (4-37 degrees C) did not vary remarkably. R-hSOD in hypothermic perfusates was stable at 4-37 degrees C for 24 h.
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PMID:Activity and stability of recombinant human superoxide dismutase in buffer solutions and hypothermic perfusates. 304 38

Vasoactive peptides contain a high proportion of proline residues which make them resistant to hydrolysis by many peptidases. However, post proline cleaving enzyme (PPCE; EC 3.4.21.26), a proline specific endopeptidase which specifically hydrolyzes internal peptide bonds on the carboxyl side of proline residues, has been shown to inactivate numerous vasoactive peptides including angiotensins, kinins, substance P, vasopressin and oxytocin. In order to determine whether PPCE could be involved in vascular metabolism of vasoactive peptides, we carried out localization and characterization studies of PPCE-like activity in hog aorta and mesenteric artery. PPCE was assayed fluorometrically at pH 7.0 using the specific PPCE substrate CBZ-Gly-Pro-4-methyl-coumarinylamide. The subcellular distribution of vascular PPCE was essentially the same as that of the cytosolic marker enzyme lactic dehydrogenase (LDH). PPCE was enriched six-fold in the cytosolic fraction (11.4 +/- 2.7 units/mg) and unlike the plasma membrane-bound proline specific exopeptidase dipeptidyl-(amino)peptidase IV (DAP IV; EC 3.4.14.5), little or no activity could be detected in the microsomal or plasma membrane fractions. Similar to PPCE characterized from other sites, vascular PPCE was stabilized and activated by dithiothreitol and EDTA, and inhibited by DFP, p-chloromercuriphenyl sulfonic acid, L-1-tosylamido-2-phenylethylchloromethyl ketone, Cu++, Ca++, and Zn++. Vascular PPCE was unaffected by inhibitors of trypsin and kallikrein (Aprotinin, ABTI), aminopeptidase M (bestatin, amastatin), neutral endopeptidase (phosphoramidon), angiotensin I converting enzyme (captopril) or carboxypeptidase N (MERGETPA). These data demonstrate that PPCE is present in vascular endothelium and/or smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vascular, post proline cleaving enzyme: metabolism of vasoactive peptides. 354 18

This paper reports the sequence of the active site peptide of penicillin-binding protein 1b from Escherichia coli. Purified penicillin-binding protein 1b was labeled with [14C]penicillin G, digested with trypsin, and partially purified by gel filtration. Upon further purification by high-pressure liquid chromatography, two radioactive peaks were observed, and the major peak, representing over 75% of the applied radioactivity, was submitted to amino acid analysis and sequencing. The sequence Ser-Ile-Gly-Ser-Leu-Ala-Lys was obtained. The active site nucleophile was identified by digesting the purified peptide with aminopeptidase M and separating the radioactive products on high-pressure liquid chromatography. Amino acid analysis confirmed that the serine residue in the middle of the sequence was covalently bonded to the [14C]penicilloyl moiety. A comparison of this sequence to active site sequences of other penicillin-binding proteins and beta-lactamases is presented.
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PMID:Purification and sequencing of the active site tryptic peptide from penicillin-binding protein 1b of Escherichia coli. 389 67

The amino acid compositions of the radioactive peptides obtained from trypsin digestion of [14C]benzylpenicillin-labeled penicillin-binding proteins (PBPs) 1A, 1B, and 3 of Escherichia coli have been obtained. Complete digestion of these peptides with a combination of aminopeptidase M and carboxypeptidase Y showed that benzylpenicillin was bound to a serine residue in each of these proteins. Comparison of the compositions of the penicillin-labeled peptides with the complete amino acid sequences of PBPs 1A, 1B, and 3 showed that the acylated serine occurs near the middle of each of the proteins, within the conserved sequence Gly-Ser-Xaa-Xaa-Lys-Pro. The sequence around the acylated serine of these high Mr PBPs shows little similarity to that around the acylated serine of the low-Mr PBPs (D-alanine carboxypeptidases) or of the class A or class C beta-lactamases, except that in all of these enzymes which interact with penicillin the acylated serine residue occurs within the sequence Ser-Xaa-Xaa-Lys.
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PMID:Sequences of the active-site peptides of three of the high-Mr penicillin-binding proteins of Escherichia coli K-12. 392 Jun 58


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