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 mechanism of the acid dimerization of alpha-chymotrypsin in solution was reexamined using a number of chemical derivatives. Blocking of the carboxyl of Tyr-146, while that of ASP-64 remained free, eliminated completely the ability of alpha-chymotrypsin to dimerize, as did methylation of His-57. O-Acetylation of Tyr-146 reduced the dimerization constant to that of gamma-chymotrypsin, and deacetylation of the other accessible tyrosines did not affect the dimerization. It is concluded that the mechanism proposed by Aune and Timasheff [Aune, K.C., and Timasheff, S.N.(1971) Biochemistry 10, 1609-1617] for the solution dimerization which involves the electrostatic interaction between the His-57 imidazolium ring and the terminal carboxyl of Tyr-146 is still most consistent with all the experimental observations. The interactions in dilute solution may differ somewhat from those observed in crystals. In particular, the two intermolecular bridges formed by sulfate ions in crystals cannot be present in solution.
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PMID:Low pH dimerization of chymotrypsin in solution. 3 Apr 71

Complexes of labelled proteinases (subtilopeptidase A, trypsin) with serum alpha 1-macroglobulin or alpha 2-macroglobulin are rapidly taken up in vitro by rabbit alveolar macrophages and peritoneal macrophages but not by mixed rabbit peripheral blood leukocytes. Enzyme, not bound to alpha 1- or alpha 2-macroglobulin, does not become associated with alveolar macrophages. Chemically inactivated subtilopeptidase A does not bind to alpha 1- or alpha 2-macroglobulin; chemically inactivated subtilopeptidase A in mixtures with alpha 1 - or alpha 2-microglobulin, does not interact with alveolar macrophages. Blocking experiments confirmed that the interaction of proteinase with alveolar macrophages is complex specific; uptake of labelled complex was prevented by the simultaneous addition of macroglobulin complexes formed with non-labelled subtilopeptidase A, subtilopeptidase B, trypsin or chymotrypsin but not by macroglobulin alone. The findings demonstrate a complex-specific interaction between proteinase-alpha-macroglobulin complexes and macrophages.
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PMID:Uptake of proteinase-alpha-macroglobulin complexes by macrophages. 120 Dec 82

Potassium and sodium leakage currents decrease when pH of the surroundings is lowering. Dicyclohexylcarbodiimide, a specific reagent of the COOH-groups does not change leakage currents. Trypsin, chymotrypsin, papain and pronase increase the sodium leakage current, not altering the potassium one. Blocking agents of the SH-groups: Hg2+ and Cd2+ decrease potassium leakage current, without changing the sodium one. Results of the proteolysis testify to that the diffusion of sodium into the cells in response is accomplished through the protein components of the membrane. The action of the blocking agents of SH-groups points out that the diffusion of potassium from the cells is realized also via the protein components of the membrane.
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PMID:[Effect of protein-modifying factors on sodium and potassium leakage currents of the secretory cell membranes]. 254 99

Mononuclear cell fibroblast interactions in the normal human lung are poorly understood. Mononuclear cells can regulate fibroblast function and blood monocytes are known to migrate to the lung and participate in pulmonary inflammation. Thus, to clarify mononuclear cell-fibroblast interactions in the normal lung, we obtained supernatants from adherent monocytes and characterized their effect on the log phase growth of human lung fibroblasts. Monocyte supernatants inhibited fibroblast growth in a dose-dependent fashion. The inhibition was the result of an approximately 16,000 MW soluble factor(s) that was heat stable, trypsin sensitive, and chymotrypsin resistant. Elaboration of the factor(s) required monocyte protein synthesis and was not restricted to a density-defined monocyte subpopulation. The inhibitory capacity of a monocyte supernatant was directly related to its ability to stimulate fibroblast prostaglandin production. Blocking fibroblast prostaglandin production reversed the inhibition of fibroblast growth caused by monocyte supernatants. Thus, monocyte inhibition of fibroblast growth may be mediated by fibroblast prostaglandin production. Recruitment of monocytes to the lung and subsequent monocyte inhibition of fibroblast growth may be important in regulating pulmonary fibrosis.
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PMID:Monocyte inhibition of lung fibroblast growth: relationship to fibroblast prostaglandin production and density-defined monocyte subpopulations. 385 5

The binding of Candida albicans yeast cells to human fibronectin (Fn), a major glycoprotein of mammalian cells, was studied using an in vitro assay. Adherence was quantitated in microtiter dishes coated with Fn to which radiolabeled yeast cells were added. Under optimum conditions of the assay, i.e., 1 mM CaCl2 and 70 micrograms Fn protein, approximately 40% of the radiolabeled yeast cells adhered to the Fn. Adherence to Fn was greater at 30 degrees C than at 4 degrees C and was greater with viable yeast cells than with heat-killed cells. Candida albicans (two strains) and C. tropicalis adhered to Fn to a greater extent than C. pseudotropicalis, C. krusei, or Saccharomyces cerevisiae. Pretreatment of C. albicans with chymotrypsin, pronase, or papain, but not pepsin, decreased adherence to Fn. Blocking experiments using mannan, sugars, or amino sugars were carried out by preabsorbing the Fn with each of the above-mentioned compounds. Candida mannan blocked adherence of C. albicans to Fn. The mannan effect was dose dependent. However, adherence of C. albicans to Fn was not significantly reduced by mannose, glucose, or several other sugars. The role of FN as a receptor for the binding of C. albicans yeast cells to buccal and vaginal epithelial cells was investigated also using an in vitro assay. We determined, using indirect fluorescent antibody techniques, that both buccal and vaginal epithelial cells possessed Fn. In addition, yeast cells, when pretreated with Fn, showed reduced adherence with buccal and vaginal cells when compared with nontreated cells. These studies may indicate a role for Fn in the adherence of C. albicans to buccal and vaginal epithelial cells.
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PMID:In vitro binding of Candida albicans yeast cells to human fibronectin. 637 Mar 99

APO-1/Fas (CD95) ligand (APO-1L) induces apoptosis in sensitive target cells. Activation-induced T cell death and Ca2(+)-independent cytotoxicity in perforin knockout mice are mediated by APO-1L. To define whether APO-1L is expressed on the surface of activated T cells and to investigate the mechanisms leading to the release of a soluble form, we developed rabbit anti-APO-1L antibodies (Ab). The purified rabbit Ab detected the mature forms of the human and mouse APO-1L of approximately 42 and 40 kDa. In addition, the Ab recognized the non-glycosylated form of APO-1L of approximately 32-33 kDa. In activated human T cells, the soluble form of APO-1L was detectable with a molecular mass of 26 kDa. Immunofluorescence of three human T lymphoblastoid cell lines showed that activation of these cells by phorbol 12-myristate 13-acetate/ionomycin induced a significant increase in cell surface APO-1L only in the presence of metalloprotease inhibitors. Zn2+, but not Ca2+, prevented the increase in surface APO-1L observed in the presence of 1,10-phenanthroline. Blocking of other classes of proteases (serine- and acid-proteases, chymotrypsin) had no effect. Increased expression of surface APO-1L by metalloprotease inhibitors was not dependent on T cell activation, as the metalloprotease inhibitors also modulated the low level of constitutive APO-1L expression. These results suggest that cell surface expression of human APO-1L is regulated by Zn2(+)-dependent metalloproteases. Cleavage of surface APO-1L may act as a regulatory mechanism to prevent accumulation of the membrane-bound form and may cause systemic effects of the APO-1L.
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PMID:Regulation of cell surface APO-1/Fas (CD95) ligand expression by metalloproteases. 754 18

The deep-sea tube worm Riftia pachyptila Jones possesses a multi-hemoglobin system with three different extracellular Hbs: two dissolved in the vascular blood, V1 (ca. 3,500 kDa) and V2 (ca. 400 kDa), and one in the coelomic fluid, C1 (ca. 400 kDa). V1 Hb consists of four heme-containing, globin chains (b-e) and four linker chains (L1-L4). V2 and C1 Hbs are exclusively built from globin chains, six for V2 (a-f) and five for C1 (a-e). The complete amino acid sequence of the isolated monomeric globin chain b, common to all Riftia Hbs, has been determined by automated Edman degradation sequencing of the peptides derived by digestion with trypsin, chymotrypsin, thermolysin, and CNBr. This polypeptide chain is composed of 144 amino acid residues, providing a M(r) of 16, 135.0 Da. Moreover, the primary sequence of chain b revealed 3 Cys residues at position 4, 75, and 134. Cys-4 and Cys-134 are located at positions where an intra-chain disulfide bridge is formed in all annelid, vestimentiferan, or pogonophoran chains, but Cys-75 is located at a unique position only found in three globin chains belonging to Lamellibrachia and Oligobrachia, a vestimentiferan and a pogonophoran. In both groups, Hbs can bind sulfide reversibly to fuel the chemosynthetic process of the symbiotic bacteria they harbor. Sulfide-binding experiments performed on purified Hb fractions (i.e., V1, V2, and C1 Hbs) suggest that free Cys residues on globin chains, and the numerous Cys found in linker chains, as determined previously by ESI-MS, may be the sulfide binding-sites. Blocking the free Cys by N-ethylmaleimide, we confirmed that free cysteines were involved in sulfide-binding but did not account for the whole sulfide-binding capacity of V1 Hb. Furthermore, a phylogenetic tree was constructed from 18 globin-like chains of annelid, vestimentiferan, and pogonophoran extracellular Hbs to clarify the systematic position of tubeworms. Riftia chain b clearly belongs to the "strain A" family with 30 to 80% identity with the other sequences analyzed. Its position in the tree confirmed a close relationship between vestimentiferan, pogonophoran, and annelid Hbs.
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PMID:Primary structure of the common polypeptide chain b from the multi-hemoglobin system of the hydrothermal vent tube worm Riftia pachyptila: an insight on the sulfide binding-site. 940 52

Chicken egg yolk phosvitin showed a remarkable antibacterial effect against Escherichia coli under thermal stress at 50 degrees C. E. coli cells (10(6)/mL) completely disappeared in 1 mL of L-broth coexisting with 0.l mg/mL phosvitin when incubated at 50 degrees C for 20 min, whereas a considerable amount of cells (10(5)/mL) survived at the same thermal stress without phosvitin. Blocking of the chelating effect of phosvitin by the addition of Ca(2+) ion displayed a protective effect against the bactericidal activity at 50 degrees C. In addition, the antibacterial activity of phosvitin was dramatically reduced by treatment with alpha-chymotrypsin, although the chelating effect remained. The surface properties, such as interfacial tension and emulsifying properties of phosvitin, which are an index of the affinity with the outer membrane, were greatly reduced by the alpha-chymotrypsin digestion. This indicates that the alpha-chymotrypsin-digested membrane-penetrating hydrophobic domains at the N- and C-terminal regions play an important role in antibacterial activity. These results suggest that a significant part of the bactericidal activity of phosvitin against E. coli resides in the synergistic effect of the high metal-chelating ability and the high surface activity under the influence of thermal stress.
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PMID:Bactericidal action of egg yolk phosvitin against Escherichia coliunder thermal stress. 1082 50

Cathepsin L-like proteases are secreted by several parasites including Taenia solium. The mechanism used by T. solium oncospheres to degrade and penetrate the intestine and infect the host is incompletely understood. It is assumed that intestinal degradation is driven by the proteolytic activity of enzymes secreted by the oncosphere. Blocking the proteolytic activity by an antibody response would prevent the oncosphere penetration and further infection. Serine and cysteine proteases including chymotrypsin, trypsin, elastase, and cathepsin L, are secreted by T. solium and Taenia saginata oncospheres when cultured in vitro, being potential vaccine candidates. However, the purification of a sufficient quantity of proteases secreted by oncospheres to conduct a vaccine trial is costly and lengthy. A 53/25 kDa cathepsin L-like fraction partially purified from T. solium cyst fluid was described previously as an important antigen for immunodiagnostics. In this study we found that this antigen is present in the T. solium oncosphere and is also secreted by the cysticercus. This protein fraction was tested for its ability to protect pigs against an oral challenge with T. solium oncospheres in a vaccine trial. IgG antibodies against the 53/25 kDa cathepsin L-like protein fraction were elicited in the vaccinated animals but did not confer protection.
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PMID:The highly antigenic 53/25 kDa Taenia solium protein fraction with cathepsin-L like activity is present in the oncosphere/cysticercus and induces non-protective IgG antibodies in pigs. 2211 17