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)

C3a anaphylatoxin is a protein fragment generated enzymatically in serum during activation of the third component of complement (C3). A four-step procedure is described for the purification of human and porcine C3a anaphylatoxins from their respective sera after activation with inulin. Because serum carboxypeptidase rapidly inactivates C3a, the inhibitor epsilon-aminocaproic acid (EACA) was added during C3 activation, thus permitting isolation of fully active C3a anaphylatoxins directly from serum. A 2000-fold purification of C3a was achieved with an average 30% recovery assuming total conversion of C3 during treatment of serum with inulin. Human C3a anaphylatoxin obtained through the action of the C3 activating enzyme of the "alternate" pathway appeared nearly identical with the C3a obtained from isolated C3 after treatment with the C4,2 enzyme of the "classical" pathway or with trypsin. Comparisons were made between various properties of human and porcine C3a anaphylatoxins. The molecular weights differed only slightly. Electrophoresis on a cellulose acetate strip at pH 8.6 indicated a difference of approximately one net charge between human and porcine C3a, with the human anaphylatoxin exhibiting the more basic behavior. Although the amino acid compositions are similar, significant differences exist. The most marked difference was the total absence of threonine residues in porcine C3a. The NH2-terminal sequences of 20 amino acid residues were examined; homology existed for 16 of the 20 positions. Although partial analysis of the primary structure of human and porcine C3a indicates approximately 80% homology, no immunological cross-reactivity between the anaphylatoxins could be detected with antisera produced to either human or porcine C3a. In spite of the structural differences, the biological activities of porcine and human C3a were essentially identical. Smooth muscle contraction, increase in vascular permeability, and release of histamine from mast cells were similarly induced by equal amounts of anaphylatoxin from either human or porcine origin. Porcine C3a, like human C3a, was shown to contain a COOH-terminal arginyl residue essential for smooth muscle contraction and for induction of histamine release from mast cells. The sequence adjacent to the COOH-terminal arginine was Leu-Ala-Arg-COOH for both humans and porcine C3a. Current evidence suggests common mechanisms exist for the generation of C3a in various animal species and that the two known C3 activating enzymes in serum exhibit trypsin-like specificity.
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PMID:Purification and partial characterization of human and porcine C3a anaphylatoxin. 80 5

Exposure of Fc fragments derived from human IgG1 myeloma proteins to acid pH rendered the region between the Cgamma2 and Cgamma3 domains transiently susceptible to cleavage by trypsin upon return to neutral pH. Trypsin covalently linked to Sepharose was used and two fragments derived from the Cgamma2 region and one from the Cgamma3 region were purified by column chromatography. On the basis of amino acid analysis, primary sequency data, antigenic properties, and m.w., one of the Cgamma2 fragments was shown to consist of two polypeptide chains of unequal mass joined by the inter-heavy chain disulfide bonds. The larger chain corresponded to a stretch of gamma-chain between Thr 223 and Lys 338 (Eu numbering) and the shorter chain to the section between Thr 223 and Lys 248. The other Cgamma2-fragment was a disulfide-linked dimer of the Thr 223 to Lys 338 sections of the paired gamma-chains. When this latter fragment was reduced under mild conditions it dissociated into monomers indicating that there was little or no noncovalent interactions between the Cgamma2 domains. The Cgamma3-fragment was shown to be a noncovalent dimer composed of the Glu 345 to Lys 349 sections of the two gamma-chains although some heterogeneity was apparent at the amino-terminus. Circular dichroism was used to probe the conformational relationships between the isolated domains and the parent Fc. The spectral properties of Fc could not be fully accounted for on the basis of the spectra observed for the isolated domains which suggested that inter-domain interaction might be significant in Fc.
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PMID:Structure and function of immunoglobulin domains. III. Isolation and characterization of a fragment corresponding to the Cgamma2 homology region of human immunoglobin G1. 81 64

An ovarian cystadenocarcinoma-associated antigen (OCAA) was found to be common to all serous and mucinous cystadenocarcinomas of the ovary. It was apparently absent in tissues of normal reproductive organs. Furthermore, OCAA was not detected in benign ovarian serous and mucinous cyst-adenomas or in any other gynecologic or nongynecologic cancers thus far tested. The antigenic determinant of OCAA was immunologically unrelated to the carcinoembryonic antigen, other known tumor antigens, or the histocompatibility antigens. We purified and partially characterized OCAA. The antigen was a high-molecular-weight glycoprotein soluble in 0.6 M perchloric acid. It consisted of about 50-60% protein (based on dry wt). Amino acid composition in OCAA was characterized by a high percentage of threonine, serine, proline, and valine. Galactose and N-acetylglucosamine were the principal carbohydrate constituents. The antigenic activity was resistant to treatment with trypsin and protease and also to treatment with DNase, RNase, and N-acetylneuraminidase. The antigenicity was considerably reduced by mild periodate oxidation.
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PMID:Tumor-associated antigen for cystadenocarcinomas of the ovary. 82 81

A glycoprotein of mol.wt. 2x10(6) was isolated in homogeneous form from pig gastric mucus by isopycnic centrifugation in CsCl but without enzymic digestion or reductive cleavage of disulphide bonds. Digestion of the purified glycoprotein with trypsin, pepsin or Pronase resulted in the formation of glycoprotein subunits, of mol.wt. 5.2x10(5)-5.8x10(5), one-quarter that of the undigested glycoprotein. The glycoprotein subunits were isolated by gel filtration and shown to contain all the carbohydrate present in the undigested glycoprotein, but 18.6-25.6% of the total amino acids originally present were lost on digestion. The relative amount of threonine, serine and proline had increased from 41% (w/w) in the undigested glycoprotein to 61-67% of the total amino acids in the glycoprotein subunits after digestion. The results support the previously proposed structure for the glycoprotein, namely that of four subunits joined by disulphide bridges. These results show the presence of two distinct regions in the glycoprotein molecule, one rich in threonine, serine and proline, which is glycosylated and resistant to proteolyis, whereas the other, with an amino acid composition more characteristic of a globular protein, is not glycosylated and is susceptible to proteolysis. In addition, the region that is susceptible to proteolysis contains the disulphide bridges which join the glycoprotein subunits together to form the gastric glycoprotein.
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PMID:The action of proteolytic enzymes on the glycoprotein from pig gastric mucus. 86 29

Two heterodetic cyclic nonapeptides, X-Cys-Thr-Lys-Ser-Asn-Pro-Pro-Gln-Cys-Y (Ia: X = Ac, Y = NH2; Ib: X = H, Y = OH), which correspond to residues 14-22 in the sequence of Bowman-Birk inhibitor, have been synthesized by Merrifield's solid-phase method. Inhibitory activities of Ia and Ib on tryptic hydrolysis of amide and ester substrates were examined. When Gly2-Lys-Gly3 and Tos-Arg-OMe were used as substrates, the values of I50 for the peptide Ia were calculated to be 3.6 micron and 40 micron, respectively. When Gly2-Lys-Gly3 was used as a substrate, the value of Ki was calculated to be 1.5 micron. Ia was hydrolyzed slowly by trypsin, losing the inhibitory activity. When the Lys-Ser bond of Ia was cleved with trypsin, the modified Ia could not be regenerated by trypsin. The linear peptide S, S'-dicarboxamidomethyl-Ia also was inactive and appeared to be a good substrate. Optical rotatory dispersion studies showed that the active fragments have characteristic conformations which were lost upon modification to inactive derivatives.
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PMID:Studies on the synthesis of proteinase inhibitors. I. Synthesis and activity of nonapeptide fragments of soybean Bowman-Birk inhibitor. 91 12

The A-protein of coliphage MS2 was purified to a state of sufficient homogeneity to study its primary structure. The NH2-terminal sequence was determined for the first 8 residues. Comparison with the reported sequence of R17 protein (Weiner, A. M., Platt, T., and Weber, K. (1972) J. Biol. Chem. 247, 3242-3251) shows a difference at position 6 where alanine in R17 is replaced by threonine in MS2. The COOH-terminal sequence was shown to be -Arg-Leu-Ser-Arg, confirming the existence of UAG as the termination codon of the maturation protein (Comtreras, R., Ysebaert, M., Min Jou, W., and Fiers, W. (19731 Nature New Biol. 241, 99-101; Vandekerckhove, J., Nolf, F., and Van Montagu, M. C. (1973) Nature New Biol. 241, 102; Remaut E., and Fiers, W. (1972) J. Mol. Biol. 71, 243-261). Peptides obtained by enzymatic hydrolysis with trypsin were fractionated by a combination of gel filtration and paper electrophoresis and chromatography. Thirty-eight peptides were analyzed for amino acid composition and sequence. They provide information for 312 of the 393 residues of the A-protein polypeptide chain.
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PMID:Sequence of the A-protein of coliphage MS2. I. Isolation of A-protein, determination of the NH2- and COOH-terminal sequences, isolation and amino acid sequence of the tryptic peptides. 91 36

Of four glycoproteins isolated from guinea pig testes, two were aspermatogenic (types I and IV) and two (types II and III) were inactive. The glycoproteins were rich in carbohydrate, varying from 41.5% to 49.5% carbohydrate by weight. Each glycoprotein had a unique amino acid composition, but in general low levels of tyrosine, tryptophan, and basic amino acids were found along with relatively high contents of serine, threonine, glutamic acid, and proline. Types I and IV glycoproteins were remarkably stable; their aspermatogenic activity was not affected by urea, trypsin, or heating at 100 degrees C in water or in 1 M HCl for 15 min. Carbohydrate analysis revealed little difference in the monosaccharide compositions of types I and IV glycoproteins, except that only the type I contained sialic acid. In contrast, types II and III glycoproteins lacked sialicacid and fucose and contained much less mannose. Both N-acetylglucosamine and N-acetylgalactosamine were present in all four glycoproteins, and they dominated in the types II and III. Fucose and at least 20-25% of the galactose appeared to occupy terminal positions in type IV glycoprotein as shown by their release after 15 min hydrolysis in 1 M HCl. All of the glycoproteins contained a relatively high percentage of galactose by weight, from 12.6 to 19.3%. The molecular weights of the glycoproteins were estimated by sodium dodecyl sulfate gel electrophoresis to be 47000, 105000 and 18000 respectively for the types I, II, and IV; type III glycoprotein showed two major bands, with molecular weights of 41500 and 22800. All the above molecular weight values are probably overestimated because of high carbohydrate content. The molecular weight of type IV glycoprotein was found to be 13000 by ultracentrifugation; a corrected value of 29000 was calculated for type I glycoprotein.
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PMID:Experimental allergic aspermatogenic orchitis. IV. Chemical properties of sperm glycoproteins isolated from guinea pig testes. 95 93

1. The preliminary phytochemical screening of the two seeds established the presence of carbohydrates and/or glycosides, flavnoids, unsaturated sterols and/or triterpenes, saponins, trypsin inhibitors and haemagglutinins. In addition, it established the absence of cardenolides, tannins, alkaloids and oxidase enzyme. 2. Certain pharmacopoeial constants, including moisture, ash, acid-insoluble ash, water-soluble ash and crude fibre were determined. 3. The two seeds were subjected to successive extractions with different organic solvents such as petroleum ether (50-70 degrees C), diethyl ether, chloroform and ethyl alcohol. The successive yields of extractives were determined. Examination of the crude extracts showed that petroleum ether extract contained sterols and/or triterpenes, while ether, chloroform, and ethyl alcohol extracts contained reducing substances. 4. General analysis of the two seeds for proteins, fats, carbohydrates, fibre and ash contents were carried out and the results were given in g/100 g dry seeds. Pigeon pea contained 25.2 g protein, 170 mg calcium and 8.9 mg iron. The protein content of kidney bean was 23 g, while calcium and iron contents were 134 mg and 8.02 mg respectively. 5. Extractions of the proteins using different solvents such as cold water, hot water, saline buffer pH 7 and sodium hydroxide was the best extractant. 6. The amino-acid content of the two seeds, whether raw or cooked, showed that they were deficient in methionine, cystine and tryptophan. Other essential amino acids were present in amounts higher than that given by the FAO provisional pattern. 7. Cooking the seeds by the popular methods used in the country resulted in an increase in the amounts of the amino acids, threonine, leucine and isoleucine, while the other amino acids present remained unchanged or decreased. It was also observed that cooking the seeds destroyed the trypsin inhibitors and haemagglutinins found in the two seeds.
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PMID:Phytochemical and nutritional studies on pigeon pea and kidney bean cultivated in Egypt. 96 10

Protein C is a vitamin K dependent protein present in bovine plasma (Stenflo, J. (1976), J. Biol. Chem. 251, 355). It is a glycoprotein (mol wt approximately 62 000) composed of a heavy chain (mol wt 41 000) and a light chain (mol wt 21 000). The heavy chain has an amino-terminal sequence of Asp-Thr-Asn-Gln and contains nearly three-fourths of the carbohydrate. The light chain has an amino-terminal sequence of Ala-Asn-Ser-Phe. Incubation of protein C with either factor X activator from Russell's viper venom or trypsin resulted in the cleavage of an Arg-Ile bond between residues 14 and 15 of the heavy chain. Concomitant with this cleavage was the formation of a serine enzyme which was inhibited by diisopropyl phosphorofluoridate. Liberation of the tetradecapeptide decreased the molecular weight of the heavy chain from about 41 000 to 39 000 and resulted in the formation of a new amino-terminal sequence of Ile-Val-Asp-Gly in the heavy chain. No change in the molecular weight of the light chain was observed during the activation reaction. These results indicate that protein C, like the four vitamin K dependent coagulation proteins, exists in plasma in a precursor form and is converted to a serine protease by hydrolysis of a specific Arg-Ile peptide bond. The biological substrate for the enzymatic form of protein C and the physiological mechanism whereby protein C is converted to a serine enzyme are not known.
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PMID:Proteolytic activation of protein C from bovine plasma. 99 Feb 50

Bovine immunoglobulins (IgG1 type) have been isolated from colostral whey. Hydrolysis by pronase, trypsin and (or) chymotrypsin yield several glycopeptides structural studies of which lead to the following results. 1. IgG1 colostral immunoglobulins possess two glycan moieties which are linked to the peptidic chain by an N-(beta-aspartyl)-N-acetylglucosaminylamine bound. 2. The peptidic sequence around the linkage region has been determined by classical methods and is as follows: Thr-Lys-Pro-Arg-Glu-Glu-Gln-Phe-Asn(Glycan)-Ser-Thr-Tyr-Arg. 3. The following procedures: partial acidic hydrolysis, periodic oxidation, hydrazinolysis-nitrous deamination, methylation and use of specific glycosidases allowed us to determine the structure of the glycan moieties which fit with the general following scheme: (see article) Thus they could be related to the general glycan structure so-called of "N-acetyllactosamine type" because they possess the pentasaccharidic core common to numerous glycoproteins Man alpha 1 leads to [Man alpha 1 leads to 6] Man beta 1 leads to 4 GlcNAc beta 1 leads to 4 GlcNAc beta 1 leads to Asn on which are conjugated 2 N-acetyllactosamine residues. Besides they present a microheterogeneity which is due to the varying number of additional N-acetylneuraminic acid and fucose residues. 4. These structures are compared to various immunoglobulin structures proposed by others: bovine serum IgG and human serum IgG, IgE and IgA.
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PMID:[Complete structure of glycopeptides isolated from IgG immunoglobulins of cow colostrum]. 99 Mar 35


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