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)

Endogenous factors inhibiting the proliferation of T-lymphocytes were investigated which may function as modulators of T-lymphocyte production within the thymus. An extract from calf thymus (T4) enriched in lymphocyte chalone arrests rat thymocytes at the G1 leads to S boundary and in the S phase of the cell cycle in short-term cultures. It also inhibits the proliferative response of human peripheral blood lymphocytes to PHA-P in a time-dependent manner, as well as the spontaneous proliferation of in vitro cultured human chronic leukaemic lymphoblasts. This crude extract contains two active moities which can be isolated by molecular filtration on Sephadex G-75 column. A species non-specific, cell line selectivity inhibitory effect is characteristic of the high molecular weight fraction (mol. wt. greater than 40,000). This activity is resistant to moderate heat treatment and trypsin but is sensitive to mild alkaline hydrolysis and to RNase A digestion. About ten protein components and a toluidine blue positive substance can be detected by analytical polyacrylamide gel electrophoresis. The active inhibitor, a proposed protein-RNA complex, might be identical with the chalone. The low molecular weight, non-dialysable factor (T4-4) inhibits [3H]thymidine incorporation into acid insoluble DNA in a cell non-specific manner. A possible relationship between the two activities is discussed.
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PMID:Endogenous thymic factors regulating cell proliferation and analysis of their mechanism of action. 14 69

Alveolar macrophages have been shown to bind glycoproteins and synthetic glycoconjugates (neoglycorpoteins) that have mannose, N-acetylglucosamine, or glucose in the exposed, nonreducing position. Galactose-terminal glycoproteins are not bound. Binding of radiolabeled ligands to cells is nearly completely impaired by the presence of an excess of yeast mannan. Binding is temperature sensitive and proceeds optimally at pH 7.0. Prior treatment of the cells with trypsin severely decreases their capacity to bind ligands. An inhibition assay has been developed, using radioiodinated glucose-albumin conjugate, agalacto-orosomucoid, beta-glucuronidase, and RNase B as ligands. Various glycoproteins have been shown to be effective inhibitors of ligand binding including horseradish peroxidase, agalacto-orosomucoid, beta-glucuronidase, ovalbumin, agalacto-fetuin, and RNase B. RNase A and asialo-fetuin are ineffective as antagonists. The results suggest the presence of a cell surface receptor on alveolar macrophages that binds glycoproteins having terminal sugars with the mannose or glucose configuration.
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PMID:Evidence for receptor-mediated binding of glycoproteins, glycoconjugates, and lysosomal glycosidases by alveolar macrophages. 27 29

The photoionization of aromatic residues constitutes a major initial photochemical reaction in the flash photolysis of proteins at gamma greater than 250 nm. The ejected electrons have been observed as eaq- and the disulphide bridge electron adduct, and also must be trapped at unidentified sites. The number of tryptophyl (or tyrosyl) residues photo-ionized at 5 musec delay is approximately equal to the number of exposed residues. The flash photolysis data have been related to inactivation by considering how photolysis of these "photolabile" residues can affect enzymic activity, based on the microstructure and available information about permanent alterations and residue specificities. This analysis indicates that hen lysozyme and papain are inactivated by photolysis of an essential Trp residue, that bovine trypsin is inactivated by photolysis of a Trp residue adjacent to the key catalytic Ser and other pathways initiated by excitation of Tyr and Cys, that the efficient photoionization of Tyr and RNase A is not an important inactivating reaction, and that aromatic residues in subtilisn Carlsberg are photosensitive.
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PMID:Flash photolysis of enzymes. 108 37

A murine IgG2a, kappa-monoclonal autoantibody (mAb) F78 is described that recognizes a novel epitope associated with small nuclear ribonucleoprotein complexes (snRNP). F78 selectively immunoprecipitated a unique pattern of small nuclear RNA (U1, U2, and U4 to U6) characterized by a marked depletion of U1 and an elevated proportion of U2 compared with known patterns immunoprecipitated by previously described anti-RNP (2.73) and anti-Sm (7.13, Y12) mAb. Analysis of immunoprecipitated RNA from extracts previously cleared with mAb F78 and probed with anti-RNP mAb 2.73 further indicated the presence of two distinct subsets of U1. Immunoblots of whole cell extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) without heating showed that F78 selectively bound to a trypsin-sensitive component of apparent m.w. greater than 120,000 which was decreased in size following RNase A treatment. The anti-Sm mAb, but not the anti-RNP mAb, also recognized this component in unheated samples. Heating before SDS-PAGE resulted in abrogation of binding to the F78 epitope. Immunoprecipitation of unlabeled or [35S]methionine-labeled cell extracts with F78 revealed the presence of most snRNP peptides, but the absence of peptide C and the 68,000 m.w. component, known to be selectively associated with U1-specific snRNP. Two-dimensional SDS-PAGE analysis of F78 immunoprecipitates confirmed that the epitope recognized by this mAb resides on a heat-dissociable complex containing snRNP-related peptides B, B', D, E, F, and G, but lacking U1-associated peptides. F78 mAb therefore defines a subset of snRNP which lack anti-RNP associated U1 RNA as well as peptides known to be selectively associated with this RNA species. It apparently recognizes an epitope associated with an assembled form of these particles and may be useful in examining structures involved in RNA processing.
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PMID:Monoclonal autoantibody recognizing a unique set of small nuclear ribonucleoprotein complexes. 244 72

Twenty Merino lambs of four age groups (1 day, 2, 4 and 7 weeks) and 8 adult Merino wethers were killed. The development of pancreatic and gastrointestinal enzymes was followed by determining RNase, amylase, lipase, trypsin, chymotrypsin and total proteolytic (azocaseinase) activity. Pancreatic protein content, rumen and abomasal pH and abomasal clotting time were also determined. Pancreatic RNase was already present in the newborn lambs and significantly rose in the first 2 weeks of life and before reaching adult values. The increase was more marked and went to higher adult values than in the pig (Baintner and Farkas, 1989). The time-course resembled that of pancreatic amylase and chymotrypsin; pancreatic trypsin and azocaseinase also showed some similarities, but pancreatic lipase had a different time course. Small intestinal RNase also changed differently; it showed a maximum at 4 weeks and had trends opposite to total proteolytic activity, indicating partial digestion of the enzyme by intestinal proteases. Rumen and caecal RNase activities may be indicative of microbial growth and fermentation rate; they showed mostly opposite tendencies in the two localities. In contrast to the pig (Baintner and Farkas, 1989), pancreatic and small intestinal trypsin:chymotrypsin ratios did not show significant increase during development in sheep.
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PMID:Development of ovine digestive enzymes with special reference to ribonuclease. 262 15

In order to study hepatocellular carcinoma-associated antigens, screening of sera and ascites was done from hepatocellular carcinoma patients having antibodies reactive with three hepatocellular carcinoma cell lines (PLC/PRF/5, Hep 3B and HA22T/VGH). The indirect immunofluorescent antibody test was used. Ten of 86 (11.6%) sera and 3 of 14 (21.4%) ascites from hepatocellular carcinoma patients showed positive bindings, whereas only 1 of 35 (2.8%) sera, none of 4 (0%) ascites from chronic hepatitis patients and 3 of 60 (5%) normal human sera had positive immunofluorescent antibody activity. The binding specificities of these positive specimens were further defined by other human cancer cell lines and mouse NIH/3T3 fibroblasts. The antinuclear antibody test against mouse liver sections was also performed. The results suggested that antigens identified by the two tests may not be identical. The nature of nuclear antigens reactive with one of the serum samples, S83, and ascites A83 were characterized. These antigens were sensitive to trypsin but not to RNase A and DNase I. Further studies by radioimmunoprecipitation and two-dimensional gel electrophoresis with serum S83 and ascites A83 showed two acidic phosphorylated antigens with molecular weights of 77 and 79 kd, which had a pI around pH 5.2. The presence of a large amount of these two phosphorylated proteins in 5 of 7 human hepatocellular carcinoma cell lines suggests that these two antigens might play some roles in the carcinogenesis or progression of human hepatocellular carcinoma.
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PMID:Nuclear antigens reacted with sera and ascites of hepatocellular carcinoma patients. 283 90

Methodology for high-performance hydrophobic interaction chromatography (HPHIC) of estrogen receptors (ER) was developed, utilizing a polyether-bonded stationary phase, which was non-ionic in nature. Using a descending salt gradient (2 M to 0 M ammonium sulphate in 40 min), ERs from human breast cancer separated into two isoforms, which retained ligand-binding domains. The same isoforms were observed with ER preparations from rat uterus. When sodium molybdate, a stabilizer of receptor structure, was incorporated into the mobile phase, it altered the ER characteristics, producing an earlier elution of one component, while the other one remained unchanged. Treatment of breast cancer cytosol with RNase A did not alter ER elution from either the hydrophobic or size-exclusion (TSK 3000 SW) columns. Modification of cysteine residues with N-ethylmaleimide led to a broad elution pattern of receptor from the hydrophobic column, implying the existence of multiple conformations of ER. Limited trypsin treatment of ER, which removes the DNA binding domain, led to the elution of only one receptor peak from the hydrophobic column. The receptor eluted at 24 min both in the presence and in the absence of sodium molybdate. Thus, at least one mechanism of the sodium molybdate effect must involve its direct interaction with ER to influence the sequence between the DNA-binding domain and the N-terminus. This also indicates that the most hydrophobic species of ER (sodium molybdate sensitive) may arise due to the interaction of the DNA-binding site with the stationary phase. Other possibilities, such as differential post-translational modifications of the receptor protein could also account for the two isoforms of ER, observed in HPHIC analysis.
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PMID:High-performance hydrophobic interaction chromatography as a means of identifying estrogen receptors expressing different binding domains. 320 33

A trypsin inhibitor was isolated from mouse lymphocytic leukemia L 1210 cells by ammonium sulphate precipitation and preparative isoelectric focusing. A 39-fold purification was attained. The inhibitor is a protein since its activity is destroyed by pronase and it binds to insolubilized trypsin. Two main forms of the inhibitor were found of pH 4.8 and 5.3. The inhibitor is copurified with DNA, although neither DNase II nor RNase A change its activity.
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PMID:Serine proteinase inhibitor from lymphocytic leukemia cells. Properties and copurification with DNA. 325 33

The biochemical properties of an in-vitro megakaryocyte growth factor called megakaryocyte potentiator (Mk-POT) were investigated. P388D1 cell conditioned medium (P388D1 CM), was used as the source of Mk-POT. The potentiator activity had an apparent mol. wt of 21 kilodaltons (kd) by gel filtration and was eluted from DEAE-Sepharose pH 8.0 with 0.15 M NaCl. Chromatofocusing revealed three active species with apparent pIs of 4.0, 5.5 and above 6.0. Most Mk-POT activity does not bind to Concanavalin A-Sepharose. Mk-POT activity is sensitive to reduction by dithiothreitol and temperatures above 90 degrees C. Treatment with trypsin, alpha-chymotrypsin and pronase also reduced the Mk-POT activity, but it was not destroyed by RNase A or neuraminidase. It is precipitated in ammonium sulphate solutions of between 60 to 70% saturation, and by 80% ethanol. The Mk-POT activity is stable in solutions of pH 5.0-9.0. The data presented here suggest that megakaryocyte potentiator is either heterogeneous in its properties or more than one molecular species may express the in-vitro Mk-POT activity found in P388D1 CM.
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PMID:Biochemical characterization of an in-vitro murine megakaryocyte growth activity: megakaryocyte potentiator. 348 43

Antibodies from 5 patients with systemic sclerosis reacted with an antigen localized to the metaphase chromatin, the cleavage furrow and the midbody of anaphase and telophase HEp-2 cells. The titer of antimidbody antibodies ranged from 1:160 to 1:1280. Four patients had systemic sclerosis and one had idiopathic Raynaud's phenomenon. In situ biochemical characterization of the antigen revealed that it was resistant to DNase I, micrococcal nuclease and RNase A, but was sensitive to trypsin treatment. The antigen remained insoluble in 400 mM acetic acid but was extracted from the cells with 400 mM hydrochloric acid. The antibody was not seen in sera from 2500 normal female blood donors, 120 patients with systemic lupus, 60 patients with rheumatoid arthritis, 15 patients with linear scleroderma or 25 patients with Raynaud's disease.
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PMID:An antigen in metaphase chromatin and the midbody of mammalian cells binds to scleroderma sera. 359 98


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