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)

Cytoskeleton-free vesicles derived from human erythrocytes were treated with trypsin, chymotrypsin, or neuraminidase followed by calcium, phosphate, or combined calcium/phosphate treatments in order to study the roles of cell surface proteins and glycoproteins in calcium/phosphate-induced cell aggregation and fusion. Vesicle aggregation (a necessary pre-cursor to membrane fusion) and subsequent membrane destabilization (an essential component of fusion) were examined by freeze-fracture electron microscopy. Enzymatic treatment alone had no effect on the morphology of the cytoskeleton-free vesicles. Neither did separate calcium nor phosphate treatments, although the treatment of the cytoskeleton-free vesicles with calcium did reduce their size slightly. Enzymatic pretreatment had no effect on the calcium-induced size changes. In contrast, the combination of calcium and phosphate drastically disrupted the membrane integrity of aggregated cytoskeleton-free vesicles at pH 7.8, although the effect was reduced at lower pH values. The extent of this membrane destabilization was independent of enzyme treatment. Our results indicate: (1) that the cell surface proteins and glycoproteins have only secondary effects on calcium/phosphate-induced cell aggregation and membrane destabilization, (2) that these processes primarily depend on the reaction between calcium and phosphate ions at the membrane surface, and (3) that cytoskeletal elements probably play no active (positive) role in the Ca2+/PO4(3-) induced erythrocyte membrane fusion process, apart from maintaining cell shape.
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PMID:Electron microscopic study of the calcium phosphate-induced aggregation and membrane destabilization of cytoskeleton-free erythrocyte vesicles. 340 81

An antibody to a high frequency antigen, made in a WES+ Black antenatal patient (Wash.), failed to react with the red cells of a presumed WES+ homozygote and is, therefore, probably antithetical to anti-WES. Like anti-WES, it reacted with papain, ficin, trypsin or neuraminidase treated cells but not with alpha-chymotrypsin or pronase treated cells and was specifically inhibited by concentrated serum. It also reacted more strongly in titration with WES- cells than with WES+ cells. The antibody is Cromer-related as it failed to react with Inab phenotype (IFC-) cells and reacted only weakly with Dr(a-) cells. Wash. cells and those of the other possible WES+ homozygote are Cr(a+) Tc(a+b-c-) Dr(a+) IFC+ but reacted only very weakly with anti-Esa.
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PMID:A 'new' Cromer-related high frequency antigen probably antithetical to WES. 343

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

The killing of Fischer rat 9L glioma in vitro by lymphokine-activated killer (LAK) cells was studied. LAK cells generated by culturing Fischer spleen cells with recombinant interleukin 2 markedly lysed glioma cells but did not kill syngeneic normal brain tissue in a chromium release microcytotoxicity assay. Susceptibility of glioma to lysis by LAK cells was markedly diminished by pretreating the glioma cells with trypsin or chymotrypsin but was unaffected by pretreatment with neuraminidase, glycosidases, or sodium periodate. These results suggest that LAK cell killing of glioma is probably tumor-selective and that a crucial cell surface determinant on glioma cells responsible for its tumor-selective lysis by LAK is a protein sensitive to trypsin and chymotrypsin.
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PMID:Lymphokine activated killer (LAK) cell-mediated lysis of murine glioma: trypsin-chymotrypsin-sensitive glioma protein is responsible for tumor-selective recognition by LAK cells. 348 96

The effects of exogenously added phospholipase A2 (PLA2) and its hydrolytic products in isolated bullfrog sciatic nerve were investigated. Nerves were pretreated for 3 h with a dose of trypsin which did not affect conduction in order to enhance penetration of the added agents. Treatment of nerves with beta-glucosidase, neuraminidase or chymotrypsin had no effect on conduction. Whereas incubation of the nerves with normal Ringers for 2 h had no significant effect on conduction, incubation with PLA2 in Ringers caused decrements in the height of the compound action potential in a dose-related manner. In addition, incubation of the nerves with 10 mg/ml lysolecithin, arachidonic acid, or docosahexaenoic acid caused marked decrements in the height of the compound action potential. Electron microscopic analysis of nerves after each treatment which caused conduction block revealed varying levels of myelin damage. Although myelin was damaged at the paranodal and/or internodal region, depending on the agents used, the axonal membrane appeared to be intact at the ultrastructural level. It was concluded that the block in conduction resulting from PLA2 was due to the formation of lysolecithin and long chain polyunsaturated fatty acids.
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PMID:Mechanism of phospholipase A2-induced conduction block in bullfrog sciatic nerve. I. Electrophysiology and morphology. 348 69

Three monoclonal antibodies (mAbs), termed SN2, SN2a and SN2b, were used in the present work to study a human T-cell leukemia-associated cell surface glycoprotein, GP37. Strong specificity of mAbs SN2, SN2a and SN2b for T leukemia cells was demonstrated by radioimmunoassay and fluorescence-activated cell sorter (FACS) analysis. GP37 was not detected on normal human peripheral blood lymphocytes, purified normal T-cells, normal thymocytes nor normal bone marrow cells. Furthermore, GP37 was barely detectable on phytohemagglutinin (PHA)- and Concanavalin A (Con A)-activated T-cells. The results indicate clinical utility of these mAbs. Competitive binding experiments show that the epitopes recognized by SN2 and SN2a are sufficiently close to each other to allow complete reciprocal inhibition of binding whereas the epitopes recognized by SN2 and SN2b are less close to allow only partial reciprocal binding inhibition. The biochemical nature of antigenic determinants defined by these mAbs was studied by treating T leukemia cells with trypsin, chymotrypsin, thermolysin, neuraminidase and mixed glycosidases. The results suggest that the antigenic determinants defined by these mAbs all consist of the protein moiety of the glycoprotein GP37. No significant antigenic modulation was observed when T leukemia cells were reacted with SN2. In a sequential immunoprecipitation experiment, a 125I-labeled leukemia antigen preparation was first treated with a rabbit anti-T leukemia antiserum. The latter had been prepared by immunizing a rabbit with a partially purified human T leukemia antigen preparation and showed a good specificity for T leukemia cells. Subsequent treatment of the labeled antigen preparation with SN2 showed that SN2 antigen had been precleared. Thus, both mouse mAb SN2 and the rabbit anti-T leukemia antiserum react with the same GP37 molecule.
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PMID:Human T-cell leukemia-associated cell surface glycoprotein GP37: studies with three monoclonal antibodies and a rabbit antiserum. 348 64

Skeletal growth factor (SGF) activity was extracted from human bone matrix by demineralization and purified under dissociative conditions using hydroxyapatite, HPLC gel-filtration and HPLC reverse-phase chromatography. Human SGF thus purified was characterized chemically and biologically. Purified human SGF stimulated chick embryo bone cell proliferation at picomolar concentrations (half maximum at 2-3 ng/ml) and had little or no activity on other cell types tested (mouse 3T3 and normal rat kidney fibroblasts, embryonic chick intestinal and human placental cells). Human SGF did not displace 125I-labeled epidermal growth factor binding to normal rat kidney cells and did not stimulate normal rat kidney cell colony formation in soft agar. Human SGF activity was sensitive to trypsin, chymotrypsin, papain, dithiothreitol and performic acid but was resistant to heat (upto 70 degrees C), pH (3-10), cyanogen bromide, alkaline phosphatase and neuraminidase and did not bind jack bean concanavalin A or kidney bean lectin. From our chemical and biological studies it appears that human SGF is different from other known polypeptide growth factors: epidermal growth factor, fibroblast growth factor, insulin, insulin-like growth factor-I, platelet-derived growth factor and transforming growth factor.
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PMID:Chemical and biological characterization of low-molecular-weight human skeletal growth factor. 349 Feb 78

A nonspecific inhibitor of macrophage migration was found in large quantities in the cell-free ascitic fluids from patients with ovarian tumours. MIF-like activity was assigned by the ability of various dilutions of ascitic fluids to inhibit migration of guinea pig macrophages from agarose droplets. The factor was purified in 3 subsequent steps including ion exchange chromatography, gel filtration, and isoelectric focusing. The data obtained indicate molecular heterogeneity according to net charge and molecular weights. The main MIF activity was found at about 45, 20, and 10 kD, respectively, and partially at less than 10 kD. Isoelectric focusing of the various MIF species revealed activity peaks in the pH range from 3.8 to 5.0. A further peak was detected at pH 6.0 in crude material. The factor was purified about 10 000-fold compared to the starting material. The action of OC-MIF was inhibited by L-fucose, and when target cells were incubated with alpha-L-fucosidase, they did not respond any longer to OC-MIF. Furthermore, purified MIF-like activity is a nondialyzable glycoprotein, sensitive to treatment with neuraminidase, chymotrypsin, trypsin and pronase, however, unaffected by incubation at 60 degrees C for 1 h. The physicochemical properties of OC-MIF activity studied are comparable to lymphocyte-derived conventional MIF.
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PMID:Inhibition of macrophage migration by a factor from ascites fluids of ovarian cancer patients. I. Biochemical characterization and purification. 351 10

Mouse tumor necrosis factor (TNF) was purified from serum through a series of steps, and each step was monitored for L-cell cytotoxicity in vitro and tumor-necrotizing activity in vivo. The two activities copurified and could not be dissociated. Purified mouse TNF has a specific activity of 2.2 X 10(7) (L-cell assay in the absence of actinomycin D) and 1 microgram causes necrosis of the standard TNF-sensitive sarcoma Meth A. TNF has a Mr of 39,000 +/- 2000 by gel filtration and a Mr of 16,000-18,000 by NaDodSO4/PAGE. Both molecular weight forms display cytotoxic and necrotizing activities. TNF has a pI of 3.9 and is destroyed by trypsin, protease, elastase, and alpha-chymotrypsin but not by neuraminidase or papain. These characteristics of nonrecombinant mouse TNF clearly resemble those of recombinant human and mouse TNF.
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PMID:Purification, characterization, and antitumor activity of nonrecombinant mouse tumor necrosis factor. 352 May 61

Epimastigotes (EPI) of Trypanosoma cruzi are highly sensitive to lysis in fresh normal human serum by the alternative complement pathway (ACP). In contrast, metacyclic trypomastigotes (CMT) derived from EPI in stationary culture fail to activate the ACP and are thus resistant to serum-mediated lysis. To investigate the nature of the parasitic surface molecules which enable infective metacyclic trypomastigotes to evade the ACP, CMT were treated with a variety of different proteolytic and glycosidic enzymes, and their sensitivity to ACP-dependent lysis was tested. Pretreatment with pronase was found to cause a near complete reversal in the resistance of CMT to serum lysis, whereas trypsin or chymotrypsin induced smaller increases in complement sensitivity. Similarly, pretreatment with N-glycanase or neuraminidase also partially abrogated the resistance of CMT to ACP-dependent lysis. The effect of these enzymes on susceptibility to complement-mediated lysis was paralleled in increased C3 and C9 deposition on the organism. In addition, electrophoretic analysis of parasite-bound C3 indicated that the hemolytically inactive fragment, iC3b, was the major form of the molecule on CMT, while the hemolytically active fragment, C3b, predominated on pronase-treated CMT. Furthermore, when C3 was deposited on the parasite surface by means of purified ACP components, 80% of C3b on pronase-pretreated CMT but only 14% of the C3b on CMT bound the amplification protein factor B with high affinity, a prerequisite for efficient ACP activation. When cultured at 37 degrees C after pronase treatment, CMT gradually regained their resistance to ACP-mediated lysis. This process was blocked if puromycin, cycloheximide, or tunicamycin were included in the culture medium. The above findings suggest that evasion of the ACP by CMT is dependent on the developmentally regulated synthesis of protein as well as N-linked carbohydrate chains. A stage-specific 90,000 to 115,000 m.w. glycoprotein doublet present on the surface of CMT was shown to be uniquely sensitive to pronase digestion. Thus, this complex, which is also recognized by a CMT-specific monoclonal antibody, may be the glycoprotein component responsible for control of ACP activation
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PMID:Evasion of the alternative complement pathway by metacyclic trypomastigotes of Trypanosoma cruzi: dependence on the developmentally regulated synthesis of surface protein and N-linked carbohydrate. 353 42


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