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)

Several classes of proteolytic enzymes were used to gain an insight into the biochemical composition of the antiotensin II (ATII) receptor prepared from bovine adrenal cortices. Exposure of the receptor fractions to trypsin reduced their capacity to bind [3H]ATII. Phospholipases A2 and C similarly inhibited the [3H]ATII binding process, while phospholipase D had no effect. Binding was stimulated following addition of phosphatidylcholine but inhibited by lysophosphatidylcholine. Neuraminidase had no influence on [3H]ATII affinity for binding, while beta-galactosidase reduced binding of the radioligand. Concanavalin A did not displace [3H]ATII bound to receptor fractions. Very little aminopeptidase activity was detected in the receptor fraction, relative to the homogenate. The data suggest that the ATII recognition sites contain protein moieties, while phospholipids may play an essential role in ATII binding. Galactose units may form a part of the ATII receptor not directly associated with the binding site. The peptidase studies indicate that ATII probably cannot be hydrolyzed to its des-Asp1 metabolite at or near the site of binding.
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PMID:Enzymatic modifications of bovine adrenocortical angiotensin II receptors. 22 26

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

An ovarian cystadenocarcinoma-associated antigen (OCAA) was found to be common to all serous and mucinous cystadenocarcinomas of the ovary. It was apparently absent in tissues of normal reproductive organs. Furthermore, OCAA was not detected in benign ovarian serous and mucinous cyst-adenomas or in any other gynecologic or nongynecologic cancers thus far tested. The antigenic determinant of OCAA was immunologically unrelated to the carcinoembryonic antigen, other known tumor antigens, or the histocompatibility antigens. We purified and partially characterized OCAA. The antigen was a high-molecular-weight glycoprotein soluble in 0.6 M perchloric acid. It consisted of about 50-60% protein (based on dry wt). Amino acid composition in OCAA was characterized by a high percentage of threonine, serine, proline, and valine. Galactose and N-acetylglucosamine were the principal carbohydrate constituents. The antigenic activity was resistant to treatment with trypsin and protease and also to treatment with DNase, RNase, and N-acetylneuraminidase. The antigenicity was considerably reduced by mild periodate oxidation.
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PMID:Tumor-associated antigen for cystadenocarcinomas of the ovary. 82 81

The Streptococcus mutans group b antigen of strain FA1 has been defined as to chemical composition and immunological specificity. The antigen in cold trichloroacetic acid extracts was fractionated on diethylaminoethyl-Sephadex A-25 at pH 8.5. Two forms were isolated: a polysaccharide and a mucoprotein. The two polymers reacted as a single substance in agar gel diffusion against specific adsorbed FA1 rabbit antisera but were separated by gel immunoelectrophoresis. No reaction with any other S. mutans or streptococcal group sera occurred. Galactose composed about one-third and galactosamine about 3% of the total weight of each polymer. Rhamnose was a major component of the polysaccharide (47%) but was present only in traces in the mucoprotein. The protein content of the latter was about 40%. No significant quantities of glycerol, phosphorus, or muramic acid were present in either case. Pepsin and trypsin had no effect on the serological specificity of the mucoprotein. d-Galactose and d-galactosamine were strong inhibitors (70%) of the precipitin reaction, whereas d-glucose, d-glucosamine, and N-acetyl-d-glucosamine inhibited between 25 and 35%. The results indicate that the antigen is a major antigenic component of the cell wall and that the specificity of the antigen resides in binding sites which contain both d-galactose and d-galactosamine. Agglutination of whole cells by specific group b antiserum indicates the antibody receptor sites of the polysaccharide antigen are at the surface of the streptococcal cell. The mucoprotein, but not the polysaccharide, was released from the cell by lysozyme. Lysis did not occur. The immunological specificity and other characteristics of the antigen establishes it as the identifying antigen of S. mutans group b.
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PMID:Structure and immunological specificity of the Streptococcus mutans group b cell wall antigen. 412 3

The effect of mild enzyme (trypsin, neuraminidase) treatment, periodate treatment and addition of carbohydrates (mono, di-, and polysaccharides) on the ingestion of Trypanosoma cruzi epimastigotes and trypomastigotes by mouse macrophages was studied. Trypsin treatment did not interfere with the ingestion of epimastigotes but did, however, increase the ingestion of trypomastigotes by mouse peritoneal macrophages. Neuraminidase and periodate treatment of the parasites increased the uptake of epi- and trypomastigote forms. The neuraminidase effect was partially blocked by galactose or N-acetylgalactosamine. Galactose, mannose, fucose, N-acetylglucosamine, and N-acetylgalactosamine had an influence on the ingestion of T. cruzi by macrophages. This effect was dependent on the strain of parasite tested, and the medium used to cultivate the epimastigotes. The results obtained, in conjunction with the work of others, suggest that glycoproteins and/or glycolipids on the parasite and/or macrophage surface are involved in the T. cruzi-macrophage interaction.
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PMID:Effect of carbohydrates, periodate and enzymes in the process of endocytosis of Trypanosoma cruzi by macrophages. 614 79

Mucus-bacterial interactions in the gastrointestinal tract and their impact on subsequent enteric infections are poorly delineated. In the present study, we have examined the binding of Salmonella typhimurium to rat intestinal mucus and characterized a mucus protein (Mucus-Rs) which specifically binds to S. typhimurium. Both virulent (1402/84), and avirulent (SF 1835) S. typhimurium were observed to bind to crude mucus, however, the virulent strain showed 6 fold more binding as compared to avirulent strain. Fractionation of crude mucus on sepharose CL-6B resolved it into three major peaks. Maximal bacterial binding was observed with a high mol. wt. glycoprotein corresponding to neutral mucin. SDS-PAGE of purified protein (termed Mucus-Rs) under non reducing conditions showed it to be a homogenous glycoprotein (mol. wt. 250 kDa), while under reducing conditions, three bands corresponding to mol. wt. of 118,75 and 60 kDa were observed. Pretreatment of Mucus-Rs with pronase, trypsin and sodium metaperiodate markedly inhibited bacterial binding. GLC analysis of Mucus-Rs showed it to contain Mannose, Glucose, Galactose, Glucosamine, Galactosamine and Sialic acid as main sugars. Competitive binding in the presence of various sugars and lectins indicated the involvement of mannose in the mucus-bacterial interactions. The Mucus-Rs binding was highly specific for S. typhimurium; no significant binding was seen with E. coli and V. cholerae. Thus, we conclude that S. typhimurium specifically binds to a 250 kDa neutral mucin of intestinal tract. This binding appears to occur via specific adhesin-receptor interactions involving bacterial pili and mannose of neutral mucin.
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PMID:Intestinal mucins: the binding sites for Salmonella typhimurium. 1071 31