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

---

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

The multicatalytic proteinase is a high molecular weight nonlysosomal proteinase which has been isolated from a variety of mammalian tissues and has been suggested to contain several distinct catalytic sites. The enzyme degrades protein and peptide substrates and can cleave bonds on the carboxyl side of basic, hydrophobic, and acidic amino acid residues. The three types of activity have been referred to as trypsin-like, chymotrypsin-like, and peptidyl-glutamyl peptide bond hydrolyzing activities, respectively. All of these proteolytic activities are associated with a single band on native polyacrylamide gels. The pH optimum of the proteinase (pH 7.5-9.5) depends on the substrate. Using synthetic peptide substrates it was possible to demonstrate two distinct activities. Trypsin-like activity is inhibited at concentrations of the peptide aldehyde inhibitors leupeptin and antipain or of N-ethylmaleimide which have little or no effect on chymotrypsin-like activity. Results of mixed-substrate experiments also suggest that there are at least two distinct types of catalytic sites. All proteolytic activity is lost following dissociation by urea or by acid treatment. Polyclonal antibodies raised against the intact multicatalytic proteinase precipitate the complex but have little effect on its proteolytic activities.
...
PMID:The multicatalytic proteinase. Multiple proteolytic activities. 274 38

The kinetics of isolation of trypsin immobilized on a dialdehyde cellulose carrier in buffer solutions with pH 7.0 and 8.0 was studied. The number of the aldehyde groups amounted to 15-60 per cent of the initial one. The kinetics of hydrolytic destruction of the collected samples with the immobilized trypsin and the carrier in buffer solutions with pH 7.0 and 8.0 was also studied. The constants of the rates of trypsin isolation from the materials and the constants of the rates of liberation into the buffer solutions of the compounds containing CO-groups were determined. The groups were used for estimating hydrolytic destruction of the materials and the time of complete destruction of the materials in the solutions.
...
PMID:[Study on the kinetics of isolation of trypsin immobilized on dialdehyde cellulose during hydrolytic destruction]. 275 76

In oxidation-dependent cytotoxicity (ODCC), cytolytic T lymphocytes (CTL) non-specifically recognize, bind to and lyse oxidized target cells (O-TC) but the precise mechanism whereby CTL react with O-TC is far from clear (Berke, G., Immunol. Rev. 1983. 72:5). Here we present evidence that CTL/O-TC interactions are blocked by aldehyde-reactive reagents such as hydroxylamine, adipic acid dihydrazide and thiocarbohydrazide and that preformed CTL/O-TC conjugates dissociate upon reduction with NaBH4, suggesting that active aldehyde groups of O-TC rather than intercellular Schiff bases are involved in the recognition and lysis of O-TC by CTL in ODCC. The aldehydes are bound to trypsin-sensitive, non-H-2 glycoproteins that appear to be different and unique in the three different target cell lines so far examined (EL4, L1210, R1.1). In view of these and previous findings we would like to suggest that in ODCC, active aldehydes react with adjacent major histocompatibility complex and perhaps other cell-surface molecules to create a multitude of modified conformations, responsible for the "polyclonal" (nonspecific) MHC recognition and lysis of O-TC by CTL, as well as for an altered pattern of H-2 antibody binding to O-TC.
...
PMID:Interaction of periodate-oxidized target cells and cytolytic T lymphocytes: a model system of "polyclonal MHC recognition". 301 6

Primary hydroxyl groups were incorporated into silica by a four-step reaction procedure which includes modification of the silica surface with gamma-glycidoxypropyltrimethoxysilane, leading to an epoxide silica; hydrolysis with acid to yield a diol silica; oxidation of the diol silica with periodate to yield a silica resin with aldehyde functions; and reduction with sodium borohydride to obtain the primary hydroxyl-containing silica. The hydroxyl groups were activated with chloroformates or carbodiimidazole. Proteins were coupled under mild conditions in high yield to these activated silica resins. Columns containing these newly developed silica derivatives were used for the fast and efficient purification of antibodies on antigen-containing silica, as well as for the purification of trypsin on a trypsin inhibitor column (or vice-versa). The effect of pressure on association and dissociation of the affinity complex is discussed.
...
PMID:Silica containing primary hydroxyl groups for high-performance affinity chromatography. 303 Jan 56

Exposure of human erythrocyte ghosts to 0.2-5 mM periodate at 0 C for 15 min resulted in an increase of thiobarbituric acid-reactive substances and fluorescent materials in the membrane. This increase was suppressed by radical scavengers, butylated hydroxytoluene and thiourea, indicating that periodate caused lipid oxidation of ghosts. A role of hemoglobin in the periodate-induced lipid oxidation of ghosts was suggested by the fact that the oxidation was augmented by hemoglobin and inhibited by an iron chelator, desferrioxamine. Treatment of ghosts with periodate caused membrane protein cross-linking with and without disulfide bridge. Erythrocytes were also susceptible to lipid oxidation by periodate, but only disulfide-mediated protein cross-linking was observed. Erythrocytes treated with neuraminidase or trypsin were less susceptible, but those treated with neuraminidase along with galactose oxidase were nearly as susceptible as untreated cells. The effect of galactose oxidase was diminished by reduction of the enzyme-treated cells with borohydride. These results indicate that the aldehyde moieties generated by periodate at the sialyl residues or those generated by galactose oxidase at the terminal galactosyl or N-acetyl galactosaminyl residues of the membrane glycoconjugates play a stimulating role in the periodate-induced membrane lipid oxidation.
...
PMID:Periodate-induced lipid oxidation of erythrocyte membranes. 303 33

Reaction of Bacillus cereus phosphonoacetaldehyde hydrolase (phosphonatase) with phosphonoacetaldehyde or acetaldehyde in the presence of NaBH4 resulted in complete loss of enzymatic activity. Treatment of phosphonatase with NaBH4 in the absence of substrate or product had no effect on catalysis. Inactivation of phosphonatase with [3H]NaBH4 and phosphonoacetaldehyde, NaBH4 and [14C]acetaldehyde, or NaBH4 and [2-3H]phosphonoacetaldehyde produced in each instance radiolabeled enzyme. The nature of the covalent modification was investigated by digesting the radiolabeled enzyme preparations with trypsin and by separating the tryptic peptides with HPLC. Analysis of the peptide fractions revealed that incorporation of the 3H- or 14C-radiolabel into the protein was reasonably selective for an amino acid residue found in a peptide fragment observed in each of the three trypsin digests. Sequence analysis of the 3H-labeled peptide fragment isolated from the digest of the [2-3H]phosphonoacetaldehyde/NaBH4-treated enzyme identified N epsilon-ethyllysine as the radiolabeled amino acid. The ability of the phosphonatase competitive inhibitor (Ki = 230 +/- 20 microM) acetonylphosphonate to protect the enzyme from phosphonoacetaldehyde/NaBH4-induced inactivation suggested that the reactive lysine residue is located in the enzyme active site. Comparison of the relative effectiveness of phosphonoacetaldehyde and acetaldehyde as phosphonatase inactivators showed that the N-ethyllysine imine that is reduced by the NaBH4 is derived from the corresponding N-(phosphonoethyl) imine. On the basis of these findings, a catalytic mechanism for for phosphonatase is proposed in which phosphonoacetaldehyde is activated for P-C bond cleavage by formation of a Schiff base with an active-site lysine. Accordingly, an N-ethyllsysine enamine rather than the high-energy acetaldehyde enolate anion is displaced from the phosphorus.
...
PMID:Investigation of the Bacillus cereus phosphonoacetaldehyde hydrolase. Evidence for a Schiff base mechanism and sequence analysis of an active-site peptide containing the catalytic lysine residue. 313 6

Rat RNK-16 leukemia cells kill YAC-1, which are the cells lysed by rodent natural killer lymphocytes. We found chymotrypsin-like proteinase ('chymase') activity in the RNK-16 dense granules that also contain cytolytic activity. The chymase activity hydrolyzed the thiobenzyl peptide substrate Suc-Phe-Leu-Phe-SBzl and, in comparison to RNK-16 tryptase activity, was selectively inhibited by three different types of serine proteinase inhibitors. The selective inhibitors were the fungal aldehyde chymostatin, the chloromethylketone Z-Gly-Leu-Phe-CH2Cl, and the mechanism-based or 'suicide' inhibitor 7-amino-4-chloro-3-(2-phenylethoxy)isocoumarin. These proteinase inhibitors also blocked RNK-16 granule-mediated cytolysis. Chymostatin, a reversible inhibitor, delayed granule-mediated cytolysis, whereas the irreversible chloromethylketone and isocoumarin proteinase inhibitors completely abrogated granule-mediated cytolysis. The two irreversible inhibitors displayed biphasic inhibition of the chymase activity, indicating that at least two chymases are present in the granules. By Northern blot analysis, we found that RNK-16 mRNA hybridized strongly with a cDNA probe of CCPI, a mouse cytotoxic T lymphocyte serine proteinase gene. These data imply that chymase activity in the cytotoxic granules is important for cytolytic function and is likely to belong to a new subfamily of serine proteinases.
...
PMID:Localization, implications for function, and gene expression of chymotrypsin-like proteinases of cytotoxic RNK-16 lymphocytes. 326 87

Microwave (MW) energy permits rapid tissue fixation for light and electron microscopy but its effects on antigen preservation have not been fully evaluated. We, therefore, fixed three samples of human skin, uterus, and cervix, and two samples of human colon and breast by MW irradiation (5 to 8 seconds) during simultaneous immersion in a dilute aldehyde mixture (2% formaldehyde and 0.05% glutaraldehyde). For comparison, similar portions of each specimen were fixed in formalin. Specimens were processed routinely and embedded in paraffin for light microscopy. Sections from each specimen were stained with hematoxylin and eosin and, by immunoperoxidase techniques, for epithelial membrane antigen, leukocyte common antigen, S-100 keratin, carcinoembryonic antigen, and factor VIII-related antigen, the latter three with and without preliminary trypsinization. Colon sections were also stained for chromogranin. In all cases, light microscopic morphology was comparable for tissues fixed by the MW method and formalin-fixed specimens, as was immunostaining for epithelial membrane antigen, leukocyte common antigen, S-100 protein, and chromogranin. Formalin-fixed tissues required trypsinization for optimal detection of keratin, carcinoembryonic antigen, and factor VIII-related antigen. In contrast, trypsin-pretreatment was not necessary to demonstrate these antigens in MW-fixed specimens and, in fact, resulted in tissue digestion. We conclude that this MW fixation method provides a means for rapidly fixing tissues for immunoperoxidase staining while preserving excellent light microscopic morphology.
...
PMID:Rapid microwave fixation of human tissues for light microscopic immunoperoxidase identification of diagnostically useful antigens. 331 39

The mode of derivatization of amino groups of proteins by glyceraldehyde, an aldotriose, depends on the presence or absence of reducing agent. In the presence of sodium cyanoborohydride, the Schiff base adducts of the aldehyde with the amino groups are reduced, and dihydroxypropylation of amino groups takes place (reductive mode). The reductively glycated lysine residue, N epsilon-(2,3-dihydroxypropyl)lysine, is a substituted alpha-amino alcohol. This alpha-amino alcoholic function of the derivatized lysine should be susceptible to periodate oxidation, and this oxidation is anticipated to result in the regeneration of the lysine residue. This aspect has been now investigated. Indeed, on mild periodate oxidation (15 mM periodate, 15 min at room temperature) of dihydroxypropylated ribonuclease A, nearly 95% of its N epsilon-(2,3-dihydroxypropyl)lysine residues were regenerated to lysine residues. The removal of the dihydroxypropyl groups by periodate oxidation could be accomplished within a wide pH range with little variation in the recovery of lysines. The possible usefulness of this reversible chemical modification procedure in the primary structural studies of proteins was investigated with a tryptic peptide of dihydroxypropylated streptococcal M5 protein, namely, DHP-T4. This 12-residue tryptic peptide contains one internal N epsilon-(dihydroxypropyl)lysine. The dihydroxypropylated peptide released most of its dihydroxypropyl groups on mild periodate oxidation. Redigestion of the periodate-treated peptide with trypsin generated the two expected peptides, demonstrating the generation of a trypsin-susceptible site. Reductive dihydroxypropylation of amino groups of RNase A resulted in the loss of its enzyme activity, the extent of inactivation increasing with the concentration of the glyceraldehyde used.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Dihydroxypropylation of amino groups of proteins: use of glyceraldehyde as a reversible agent for reductive alkylation. 365 95

A trypsin digest of denatured NaB3H4-reduced native bovine periodontal ligament was prepared and fractionated by gel filtration and cellulose ion-exchange column chromatography. Prior to trypsin digestion, a complete acid hydrolysate was subjected to analyses for nonreducible stable and reducible intermolecular cross-links. Minute amounts of the former and significant amounts of the reduced cross-links dihydroxylysinonorleucine (1.1 mol/mol of collagen), hydroxylysinonorleucine (0.9 mol/mol of collagen), and histidinohydroxymerodesmosine (0.6 mol/mol of collagen) were found. The covalent intermolecular cross-linked two-chained peptides that were isolated were subjected to amino acid and sequence analyses. The structures for the different two-chained linked peptides were alpha 1CB4-5(76-90)[Hyl-87] X alpha 1CB6-(993-22c)[Lysald-16c], alpha 1CB4-5(76-90)[Hyl-87] X alpha 1CB6(993-22c)[Hylald-16c], alpha 2CB4(76-90)[Hyl-87] X alpha 1CB6(993-22c)[Lysald-16c], and alpha 2CB4(76-90)[Hyl-87] X alpha 1CB6(993-22c)[Hylald-16c]. The cross-link in each peptide was glycosylated. This is the first characterization by sequence analysis of a cross-link involving Hyl-87 in an alpha 2 chain in collagen. A stoichiometric conversion of residue 16c aldehyde to an intermolecular cross-link in each of the COOH-terminal nonhelical peptide regions of both alpha 1 chains in a molecule of type I collagen was found. The ratio of alpha 1 to alpha 2 intermolecularly cross-linked chains involved was 3.3:1, indicating a stereospecific three-dimensional molecular packing of type I collagen molecules in bovine periodontal ligament.
...
PMID:Intermolecular cross-linking and stereospecific molecular packing in type I collagen fibrils of the periodontal ligament. 376 22


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---