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:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The production of urea and ornithine is increased greatly in spleen cell cultures of an allograft recipient in the presence of donor cells (secondary MLC) in comparison to that of primary MLC (without previous allograft). This phenomenon appears after 24 hr of culture and reaches its maximum at 48 hr. The greatest increase in urea production is observed when the recipient spleen cells are collected at the time of allograft rejection. To obtain this extra production of urea, the stimulating cells in MLC should specifically be of the donor type or at least bear one homology with donor cells at the K or D locus. The increased production of urea and ornithine during MLC results from the action of a lymphokine released by recipient cells in the presence of donor cells. This factor acts upon cells present in bone marrow, spleen, and elicited peritoneal cells but is absent or is present in smaller quantities in thymus and lymph node cells. Target cells of this factor possess numerous macrophage features and could be immature cells of the macrophage line. The lymphokine responsible for this phenomenon is heat-stable, destroyed by trypsin, chymotrypsin, and neuraminidase, and has a m.w. around 32,000. It acts upon its target cells by increasing arginase activity, which results in the production of a large amount of ornithine, an important precursor of polyamine biosynthesis.
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PMID:Evidence for a lymphokine enhancing arginase activity during allograft rejection. 618 26

In this study, the effect of sixteen different enzymes on serum C1 and its subcomponents was investigated. The sixteen enzymes could be divided into three groups. First, enzymes which activate native C1: trypsin (optimal concentration 2.4 x 10(-4) mM); alpha-chymotrypsin (2.3 x 10(3) mM); thrombin (1.0 x 10(-5) mM); plasmin (1.9 x 10(-5) mM); elastase (5.8 x 10(-5) mM); pronase (3.0 x 10(-6) mM). All these enzymes are serine esterase and activate native serum C1 bound to EAC4 at the given concentration within 10 min at 30 degrees C. Furthermore, native C1 inhibited by a pentosanpolysulfoester, Sp54, is unable to undergo the internal activation but can be externally activated by the serine esterases. Second, enzymes which do not activate native C1 but result in a dose and time-dependent loss of C1 activity: collagenase; pepsin; carboxypeptidase B. Third, enzymes which have no effect on C1 and C1: Lysozyme; neuraminidase; beta-galactosidase; L-amino acid oxidase; arginase; streptokinase, and acetylcholinesterase.
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PMID:Activation of the first component of complement, C1: comparison of the effect of sixteen different enzymes on serum C1. 619 90

Serum-free medium conditioned by the normal rat kidney (NRK) cell line contains colony-stimulating factors (CSF) that stimulate the in vitro formation of granulocyte and macrophage colonies from rat, mouse, and human marrow. There are two types of CSF: NRK-CSF I stimulates rat and mouse marrow, while NRK-CSF II stimulates the human marrow. The NRK-CSF I has been partially purified to a specific activity of 5 X 10(7) units/mg by employing methods such as preparative isoelectrofocusing, gel filtration chromatography, and preparative gel electrophoresis. It has an isoelectric point of 5.1 and an apparent molecular weight of 35,000 daltons as estimated by gel filtration. It is stable at 50 degrees C for 30 min and relatively resistant to papain, but highly sensitive to trypsin, chymotrypsin, and subtilisin. The secretion of CSF by NRK cells is inhibited by actinomycin D (0.5 micrograms/ml) and cycloheximide (0.5 micrograms/ml), but not by cytosine arabinoside (5 micrograms/ml). Although the CSF activity is inactivated by periodate oxidation (5 mM), thus suggesting its glycoprotein nature, treatment of the CSF with neuraminidase and other glycosidases has no effect on its activity. Anti-NRK-CSF I antibody inhibits the rat/mouse-active CSF from all rat sources, but has no effect on the human-active CSF. Comparative studies with CSF from media conditioned by the transformed cell line (442) and from rat lung and spleen have shown that CSF I from different rat sources share similar isoelectric points, molecular weights, and immunological properties.
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PMID:Granulocyte-macrophage colony-stimulating factor from cultured normal rat kidney cell line. 620 75

Previous studies established that brain microsomes catalyze the transfer of [35S]sulfate from 3'-phosphoadenosine 5'-phospho[35S]sulfate to an O-linked oligosaccharide chain of a membrane glycoprotein and sulfamino groups of a membrane-associated proteoheparan sulfate (R. R. Miller and C. J. Waechter (1979) Arch. Biochem. Biophys. 198, 31-41). A large fraction of the proteoheparan [35S]sulfate can be released by treating the enzymatically labeled membranes from calf brain with 1 M NaCl. The salt-extracted 35S-labeled proteoglycan has been partially purified by a combination of ion-exchange and gel filtration chromatography. Based on chromatographic analyses, the 35S-labeled proteoglycan labeled in vitro is proposed to be a family of proteoheparan [35S]sulfates having an average molecular weight estimated to be 55,000. Variation in the length of the 35S-labeled polysaccharide chains partially accounts for the differences in molecular size of the proteoheparan [35S]sulfates. Binding studies reveal that the intact proteoheparan [35S]sulfates, as well as the free 35S-labeled polysaccharides released by mild alkali treatment, rapidly reassociate with calf brain membrane preparations. The association with calf brain membranes is saturable and reversible. Consistent with the binding being a specific interaction, only iduronic acid-containing glycosaminoglycans inhibit the association of the 35S-labeled proteoglycan with calf brain membranes and facilitate the disassociation. Neither the binding of the 35S-labeled proteoglycan to membranes nor the displacement was affected by hyaluronic acid, chondroitin 4-sulfate, or chondroitin 6-sulfate. The binding of the enzymatically labeled proteoheparan sulfate is reduced by preincubating membranes with either trypsin or chymotrypsin, but not with neuraminidase or phospholipase D. These results suggest that at least one class of proteoheparan sulfates could be specifically bound to one or more brain membrane proteins. The results also suggest a role for iduronosyl residues, and perhaps the stereochemical relationship of the carboxyl group to the O-sulfate moiety at C-2, in the recognition process.
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PMID:Structural features and some binding properties of proteoheparan sulfate enzymatically labeled by calf brain microsomes. 623 46

The binding of mouse epidermal growth factor-urogastrone (EGF-URO) to membranes from term human placenta is peptide-specific, saturable (about 20 pmol of EGF-URO bound maximally/mg of protein), reversible, and of high affinity (KD about 400 pM). Optimal binding is observed at pH 7.6. At low pH (3.5 to 5.0). EGF-URO can be reversibly dissociated from the receptor; however, exposure to pH < 3 irreversibly inactivates the receptor. The binding, which does not exhibit ligand cooperativity, exhibits an association rate constant of 6.1 x 10(-4) s-1 and a dissociation rate constant of 6.1 x 10(-4) s-1. The dissociation constant determined from the rate constants, 240 pM, is in reasonable agreement with the constant estimated by equilibrium methods. Both monovalent and divalent cations augment EGF-URO binding 2- to 3-fold. Although in general, divalent cations enhance binding at lower concentrations (optimum, 5 mM) than do monovalent cations (optimum, approximately 80 mM), there is no cation-specific effect. Neither guanine nor adenine nucleotides affect EGF-URO binding. Whereas the proteolytic enzymes (trypsin, chymotrypsin, papain, and pepsin) inactivate the receptor, neuraminidase and phospholipases A2, C, and D augment EGF-URO binding. Neuraminidase increases the number of available sites without affecting ligand affinity. Wheat germ agglutinin, concanavalin A, and phytohemagglutinin all compete for the binding of EGF-URO. The data complement previous observations of EGF-URO binding obtained in intact cells and provide a basis for the solubilization, characterization, and isolation of this receptor from a rich tissue source.
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PMID:Characterization of the receptor for epidermal growth factor-urogastrone in human placenta membranes. 625 85

Preincubation for 10-30 min with trypsin, pronase, chymotrypsin, or papain primed macrophages to undergo a twofold to sixfold increase in oxidative metabolism, measured as release of superoxide anion or hydrogen peroxide, during stimulation by phorbol myristate acetate or ingestion of Candida parapsilosis. Preincubation of macrophages with inactivated proteases, nonenzyme proteins, or neuraminidase did not affect their oxidase response. Exposure of macrophages to proteases generated at sites of inflammation could prime these cells for a more effective oxidase response to phagocytosis or for greater tissue damage from release of toxic oxygen metabolites.
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PMID:Priming of macrophages for enhanced oxidative metabolism by exposure to proteolytic enzymes. 626 88

The lymphokine activity, macrophage aggregation factor (MAgF) has been investigated further. Activity was consistently found in 24 hr test, but not control, spleen cell culture supernatants. This was higher after dialysis against water, than in the original culture supernatants. MAgF was heat-stable, inactivated by alpha-chymotrypsin, partially inactivated by trypsin and not affected by neuraminidase. Activity was recovered from the supernatant after protein precipitation with 1 M perchloric acid, leading to a modest purification. Activity was only marginally reduced after treatment with periodate, and was not absorbed by Concanavalin A-Sepharose. Polyacrylamide gel electrophoresis showed that MAgF migrated cathodally to albumin. Aggregation, as measured in a batch centrifugation assay, was an expression both of cell-substrate and cell--cell adhesion.
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PMID:Macrophage aggregation factor: some properties. 628 38

Treatment of peripheral blood lymphocytes from normal donors with small amounts of purified Sendai virions results in enhanced cellular cytotoxicity in vitro to uninfected tissue culture target cells (virus-dependent cellular cytotoxicity (VDCC)), without any obvious correlation to the natural cytotoxicity (NK) displayed by the lymphocytes in the absence of virus. Removal from the virions of the two surface components present in the viral envelope, the HN glycoprotein (gp 71), carrying haemagglutinating and neuraminidase activity, and the F glycoprotein (gp 49), carrying fusion activity, by treatment with pronase abrogated their capacity to induce VDCC. Similar results were obtained when virions lacking the HN glycoprotein after treatment with chymotrypsin were added to the lymphocytes. In contrast, treatment of the virus particles with trypsin, which removed the F glycoprotein, did not affect their capacity to induce VDCC. When the solubilized and separated peplomers were used for lymphocyte treatment, either alone or in combination, the purified HN glycoprotein had full capacity to induce VDCC, whereas the F glycoprotein was inactive. These results suggest that the HM peplomer is solely or primarily responsible for the cytolytic activity arising in non-sensitized lymphocytes when confronted with certain viruses.
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PMID:Sendai-virus-induced cell-mediated cytotoxicity in vitro. The role of viral glycoproteins in cell-mediated cytotoxicity. 630 Sep 94

Encephalomyocarditis and influenza viruses attach to human erythrocytes causing haemagglutination. The receptor for both viruses on these cells is the major membrane sialoglycoprotein, glycophorin, solubilized preparations of which inhibit haemagglutination by either virus. We show here that glycophorin preparations inhibited haemagglutination of both viruses, even after the preparations were digested with chymotrypsin. To determine which component(s) in the digest exhibited activity, peptides separated by gel filtration were assayed for haemagglutination inhibition; one peptide only, CH-0, was active. A tentative structure was deduced for CH-0 from amino acid and sialic acid analyses. It was already known that neuraminidase treatment of erythrocytes or glycophorin prevents interaction with either virus, suggesting that sialic acid may form part of the active binding site in the receptor. However, receptor activity requires more than the presence of a particular arrangement of sialic acid since the arrangement in CH-0 was identical to that in two other inactive chymotryptic peptides. Examination by gel filtration, sucrose density gradient centrifugation and SDS-polyacrylamide gel electrophoresis demonstrated that Ch-0 readily aggregated, unlike the inactive peptides. It was proposed that the CH-0 chymotryptic peptide showed receptor-like activity (inhibited haemagglutination) because its tendency to aggregate allowed strong multivalent binding with virus particles.
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PMID:A sialoglycopeptide from human erythrocytes with receptor-like properties for encephalomyocarditis and influenza viruses. 630 11

F (fusion) and HANA (hemagglutinin and neuraminidase) glycoproteins of HVJ (Sendai virus) were purified and characterized. The NH2-terminal hydrophobic region of the F1 (larger) subunit of F (fusion)-glycoprotein seems to be required for the hemolytic and cell fusion-inducing activity of the virus for the following reasons. (1) Selective splitting off of a 2,500-3,500 dalton segment from the NH2-terminal region of F1 by chymotrypsin or thermolysin resulted in inactivation of the biological activities of HVJ. (2) At least a part of this region may be exposed to the surrounding medium, since it is preferentially iodinated and is easily split by aminopeptidase M, chymotrypsin, and thermolysin. Tryptic digestion, which does not remove the NH2-terminal region but produce nicking of F1 subunit to subfragments F1a (larger one) and F1b (smaller one), resulted in substantial structural changes evidenced by circular dichroism measurement and iodination by lactoperoxidase method. Trypsin-digested F seems to have the NH2-terminal hydrophobic region buried within hydrophobic interior of the protein (or in the lipid bilayers). Based on these and other results, we propose a hypothesis featuring direct interaction of the hydrophbic region with the lipid bilayers of the target-cell membrane as an important step in fusion reactions between the viral envelope and cell membranes.
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PMID:Viral proteins in cell fusion. 631 Aug 22


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