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)

Fractions of porcine cerebral cortex extract separated by molecular weight on a Sephadex G-75 column were tested for their activities and potencies to inhibit [3H]benzodiazepine binding to rat brain homogenates. The fractions spanned molecular weights from 500 to 100,000. A potent inhibitor (benzodiazepine-competitive factor I, BCF-I) was discovered in the fraction containing substances with molecular weights from 40,000 to 70,000. Equilibrium binding studies indicated that BCF-I was a competitive inhibitor, making it a candidate as a benzodiazepine endogenous factor or profactor. BCF-I was heat stable, but trypsin digestion destroyed its activity. Another inhibitory fraction (BCF-II) was 1/5th as active as BCF-I and contained substances with molecular weights from 1000 to 2000.
Proc Natl Acad Sci U S A 1978 Dec
PMID:Competitive inhibition of benzodiazepine binding by fractions from porcine brain. 3 39

When the jelly-less eggs removed from the most cephalic region of the oviduct (pars recta) of the toad Bufo arenarum were inseminated at a high sperm concentration, high frequencies of fertilization were obtained. On the other hand, control eggs removed from the pleuroperitoneal cavity (coelomic eggs)) were neither fertilized upon insemination under identical conditions, nor with the water extract of the jelly. Under these inseminating conditions, however, a high frequency of fertilization was obtained when coelomic eggs were preincubated in the presence of the fluid secreted by the epithelium of the pars recta or of an extract prepared from pars recta homogenate. Experimental evidence is presented showing that the component responsible for this effect acts on the vitelline envelope of the egg, increasing its susceptibility to sperm lysin. It is probable, therefore, that it induces successful fertilization of coelomic eggs by making the vitelline envelope more easily penetrable by sperm. The active factor was partially purified by Sephadex chromatography. The product obtained was of high activity and, as judged by its inhibition with soybean trypsin inhibitor and lima-bean trypsin inhibitor, it is likely to be a trypsin-like enzyme. The molecular weight of the factor was estimated to be 47000 by Sephadex chromatography. Secretion of the pars recta factor is hypophysis-dependent and its activity is not influenced by pH within the range testes (6.0--8.4).
J Embryol Exp Morphol 1978 Dec
PMID:A trypsin-like oviducal proteinase involved in Bufo arenarum fertilization. 3 7

Methionyl-tRNA synthetase from Escherichia coli can react with periodate-treated tRNA to form a Schiff's base through the epsilon-amino group of a lysine within the enzymic active center and the 2',3'-aldehyde groups created at the 3'-terminal ribose of tRNA. At alkaline pH, the Schiff's base equilibrium can be continuously and specifically displaced by reduction in situ with sodium cyanohydridoborate, which on the other hand leaves intact the reacting aldehyde groups of oxidized tRNA. The effects of temperature, pH and of reducing agent concentration on the rate and extent of reduction of the Schiff's base are analysed. Conditions are described (37 degrees C, pH 8.0, in the presence of 1 mM cyanohydridoborate) which allowed rapid and complete conversion of the monomeric trypsin-modified methionyl-tRNA synthetase into its 1:1 covalent complex with tRNAfMet.
Eur J Biochem 1979 Dec
PMID:Complete inactivation and labeling of methionyl-tRNA synthetase by periodate-treated initiator tRNA in the presence of sodium cyanohydridoborate. 4 39

Besides active renin an inactive form of renin could be demonstrated in uterine tissue. On gel filtration it was eluted as a molecule of slightly higher molecular weight than active renin, and it could be irreversibly activated by acidification at 37 degrees C. The activation had a pH optimum between pH 3.8 and pH 5.3. Acid activated uterine renin was found identical to active uterine renin by 1) the formation of angiotensin I with time after addition of rat substrate, 2) the pressor response in the rat, 3) neutralization by antirenin and 4) similar Michaelian constants. Repeated freezing and thawing, acidification at 4 degrees C and dialysis against 4 mol/l NaCl did not give any activation. A lower rate of activation of diluted samples and activation by trypsin at pH 7.4 suggest that proteolytic enzymes are involved in the activation.
Acta Endocrinol (Copenh) 1979 Dec
PMID:The mechanism of the acid activation of rabbit uterine renin. 4 44

We have characterized the binding of gamma-glutamyltransferase to three insolubilized lectins. Optimal binding was achieved in 2 hours at 25 degrees C for concanavalin A and at 4 derees C for ricinus communis agglutinin 120 and wheat germ agglutinin,and was also a function of the ratio of lectin protein to gamma-glutamyltransferase protein. The interaction of gamma-glutamyltransferase with these three lectins is specific, and release of bound enzyme by carbohydrates follows the same general order of specificity previously observed for the competition between mono or polysaccharides for the lectin carbohydrate binding sites. The binding of trypsin-solubilized liver gamma-glutamyltransferase to the three insolubilized lectins was virtually identical to that of detergent solubilized enzyme. We propose, therefore, that the release by proteolytic enzymes, of gamma-glutamyltransferase from plasma membrane matrix does not significantly alter its carbohydrate structure. We obtained great differences in binding to the three lectins between the liver, kidney, pancreatic and duodenal isoenzymes of gamma-glutamyltransferase. From this data we conclude that carbohydrate content and topography are important distinguishing features of gamma-glutamyltransferase isoenzymes.
Clin Biochem 1979 Dec
PMID:Interaction of gamma-glutamyltransferase from human tissues with insolubilized lectins. 4 83

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.
Kidney Int 1979 Dec
PMID:Further observations on a low-molecular-weight natriuretic substance in the urine of normal man. 4 87

The essential steps of the 33258 Hoechst-Giemsa method for differential chromatid staining consist of (1) 33258 Hoechst treatment, (2) exposure to light, and (3) Giemsa staining. The staining was shown to be a function of the concentration of 33258 Hoechst and the light exposure. The dye was successfully replaced by various metachromatic dyes such as thionine. Two simple methods are proposed. Failure of the pale stained chromatids to restore Giemsa affinity with urea and trypsin and the diminished Feulgen reaction after light exposure suggest that not masking proteins but photolysis of the BrdU-incorporation chromatid components in the present of photosensitive dyes play a role in the differential staining.
Chromosoma 1975 Dec 10
PMID:Simple differential Giemsa staining of sister chromatids after treatment with photosensitive dyes and exposure to light and the mechanism of staining. 5 33

Two separate lymphocyte populations, each bearing easily detectable surface immunoglobulin, have been detected in human peripheral blood. The first, B cells, has surface determinants that are stable at 37degreeC, but are removed by pronase and regenerate in culture. The cells are nylon adherent and have a receptor for C3, and studies with unit gravity sedimentation indicate they are mostly small lymphocytes. B cells comprise 9.5% of the total lymphocytes, with the normal range from 3-16%. As many or more lymphocytes lack membrane-incorporated Ig determinants but have an Fc receptor that binds IgG1 and IgG3 in normal serum maximally at 4degreeC. This receptor for cytophilic IgG is removed by pronase but not by trypsin. The second population has been named L lymphocytes because of membrane-labile IgG determinants. L cells do not adhere to nylon, do not form rosettes with sheep erythrocytes sensitized with antibody and mouse complement, and are larger than small lymphocytes. These lymphocytes with cold-reactive Fc receptors for serum IgG do not form E-rosettes or respond to phytohemaggutinin. Since L cells do not have surface markers of T and B lymphocytes, it is likely that they comprise a separate population.
J Clin Invest 1975 Dec
PMID:Characterizaiton of two populations of human lymphocytes bearing easily detectable surface immunoglobulin. 5 40

The antigenic properties of the cyanogen bromide peptide F-CB3 from bovine fibrinogen alpha-chain were studied in radioimmune assays with rabbit antibodies to fibrinogen or to peptide F-CB3. Both fibrinogen and peptide F-CB3 were indistinguishable in inhibition and dissociation tests. Modification of the single disulfide bridge in peptide F-CB3 either by reduction or by cleavage with cyanide was not accompanied by loss of serologic activity. Inhibition studies with three individual fragments obtained after cyanide cleavage (molecular weight range 7000 to 23000) indicated the presence of at least three distinct antigenic determinants in peptide F-CB3. After trypsin digestion of peptide F-CB3 still 75% of its maximal inhibiting capacity was retained. Lack of change in antigenic activity of peptide F-CB3 after release from the fibrinogen molecule by cyanogen bromide and upon further fragmentation is presumably due to the presence of several sequential antigenic determinants but the presence of conformational determinants could not be entirely excluded. Since no cross-reaction was observed between bovine and human peptides F-B3 one may expect considerable variation in their amino acid sequence.
Eur J Biochem 1975 Dec 01
PMID:Antigenic structure of the cyanogen bromide peptide F-CB3 from fibrinogen alpha-chain. 5 58

Cross-reactive antigens of clover roots and Rhizobium trifolii were detected on their cell surfaces by tube agglutination, immunofluorescent, and radioimmunoassay techniques. Anti-clover root antiserum had a higher agglutinating titer with infective strains of R. trifolii than with noninfective strains. The root antiserum previously adsorbed with noninfective R. trifolii cells remained reactive only with infective cells, including infective revertants. When adsorbed with infective cells, the root antiserum was reactive with neither infective nor noninfective cells. Other Rhizobium species incapable of infecting clover did not demonstrate surface antigens cross-reactive with clover. Radioimmunoassay indicated twice as much antigenic cross-reactivity of clover roots and R. trifolii 403 (infective) than R. trifolii Bart A (noninfective). Immunofluorescence with anti-R. trifolii (infective) antiserum was detected on the exposed surface of the root epidermal cells and diminished at the root meristem. The immunofluorescent crossreaction on clover roots was totally removed by adsorption of anti-R. trifolii (infective) antiserum with encapsulated infective cells but not with noninfective cells. The cross-reactive capsular antigens from R. trifolii strains were extracted and purified. The ability of these antigens to induce clover root hair deformation was much greater when they were obtained from the infective than noninfective strains. The cross-reactive capsular antigen of R. trifolii 403 was characterized as a high-molecular-weight (greater than 4.6 times 10(6) daltons), beta-linked, acidic heteropolysaccharide containing 2-deoxyglucose, galactose, glucose, and glucuronic acid. A soluble, nondialyzable, substance (clover lectin) capable of binding to the cross-reactive antigen and agglutinating only infective cells of R. trifolii was extracted from white clover seeds. This lectin was sensitive to heat, Pronase, and trypsin. inhibition studies indicated that 2-deoxyglucose was the most probable haptenic determinant of the cross-reactive capsular antigen capable of binding to the root antiserum and the clover lectin. A model is proposed suggesting the preferential adsorption of infective versus noninfective cells of R. trifolii on the surface of clover roots by a cross-bridging of their common surface antigens with a multivalent clover lectin.
Appl Microbiol 1975 Dec
PMID:Cross-reactive antigens and lectin as determinants of symbiotic specificity in the Rhizobium-clover association. 5


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