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 complete amino acid sequence and the location of disulfide bonds of a lectin from Japanese frog (Rana japonica) eggs, which specifically agglutinates transformed cells, are presented. The sequence was determined by analysis of peptides generated by digestion of the S-carboxyamidomethylated protein with Achromobacter protease I, or chymotrypsin, and by chemical cleavage with BNPS-skatole or cyanogen bromide. The lectin is a single-chain protein consisting of 111 residues, with a pyroglutamyl residue at the amino terminus. Four disulfide bonds link half-cystinyl residue 19 to 72, 34 to 82, 52 to 97, and 94 to 111. The sequence and the location of the disulfide bonds are highly homologous to those of bull frog (Rana catesbeiana) egg S-lectin. They are also homologous to human angiogenin, a tumor angiogenesis factor, and a family of pancreatic ribonucleases.
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PMID:Amino acid sequence of a lectin from Japanese frog (Rana japonica) eggs. 222 5

Echinonectin (EN) is a 230-kDa extracellular matrix glycoprotein found in the hyaline layer of sea urchin embryos. Dissociated embryonic cells attached strongly to EN-coated microtiter wells in a centrifugal-based in vitro adhesion assay, suggesting that EN is one of the hyaline layer proteins to which cells adhere in vivo (Alliegro et al., 1988). The present study examines the molecular properties of that adhesion using monoclonal antibodies as probes to block cell attachment, and also demonstrates that EN possesses lectin activity. EN binds tenaciously to agarose-based chromatography resins, such as Sepharose. The sugar-binding activity is associated with the polypeptide component of EN, and not with the carbohydrate moiety. Binding is inhibited with galactose and fucoidan, but not with glucose or locust bean gum. Although functional sites both for polysaccharide binding and for cell attachment are present on each subunit of the EN molecule, the sites appear to be functionally distinct because galactose and fucoidan are completely without effect on cell attachment in vitro. Proteolytic digestion of EN yields a highly limited set of immunoreactive peptides. Digestion with trypsin yields a 20-kDa fragment, chymotrypsin, a doublet at 20 kDa, and 20- and 23-kDa fragments with thermolysin. McAb's directed against these peptides block cell adhesion in vitro, suggesting that they possess the cell attachment domain of EN. This is supported by the observations that trypsin-digested EN is an effective substrate in adhesion assays and that adhesion to the tryptic fragments is also blocked by McAb's to the 20-kDa domain.
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PMID:In vitro biological activities of echinonectin. 232 45

The amino-acid sequence of a lectin isolated from the coelomic fluid of the acorn barnacle Megabalanus rosa has been determined. The lectin (Mr 140,000) is a multimeric protein whose subunit consists of 173 amino acids and one carbohydrate chain attached to Asn-39. The amino-acid sequence was determined by the manual sequencing of peptides derived from the protein by digestion with Staphylococcus aureus V8 proteinase, lysine endopeptidase and chymotrypsin, as well as fragments produced by cleavage with cyanogen bromide. The amino-acid sequence of the lectin was compared with the sequence of one (Mr 64,000) of the multiple lectins of M. rosa. They are distinct molecules in spite of a significant homology in their amino-acid sequences. The amino-acid sequence includes some regions homologous to those in other invertebrate lectins, such as sea urchin and flesh fly lectins, and vertebrate lectins. This is the first report to show the amino-acid sequence of multiple lectins isolated from an invertebrate.
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PMID:The amino-acid sequence of multiple lectins of the acorn barnacle Megabalanus rosa and its homology with animal lectins. 235

Lectin binding to formalin-fixed, paraffin-embedded tissue can often be enhanced by pre-treatment of the sections with proteolytic enzymes. However, the pattern of staining may be profoundly influenced by the type of enzyme preparation which is used. Sites of binding of thirteen different lectins to murine ovary and thyroid gland were studied after exposure of tissue sections to crude trypsin, purified trypsin, purified alpha-chymotrypsin, pepsin, protease VII, papain, bromelain, thermolysin or elastase. With most lectins, the results obtained were similar regardless of which enzyme was used for proteolytic digestion. However, the pattern of binding of soy bean lectin to the ovary and of concanavalin A and common pea lectin to the thyroid gland was highly dependent upon the enzyme used to pre-treat the sections. In both tissues, the staining pattern seen in untreated frozen sections was similar to that found in formalin-fixed, paraffin-embedded material digested with purified trypsin, but was different from that observed after exposure of processed sections to crude trypsin. The location of binding sites after treatment of paraffin sections with chymotrypsin was the same as that after digestion with crude trypsin. Results obtained after the use of other proteolytic enzymes varied according to the tissue being studied. These findings imply that the effect of treatment with crude trypsin is due to contaminating chymotrypsin, and demonstrate that the use of purified trypsin may have advantages over other proteolytic enzymes in lectin histochemistry. The observations may also apply to other related cytochemical techniques such as immunocytochemistry.
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PMID:Proteolysis and lectin histochemistry. 244 Aug 34

Although antigen-reactive T lymphocytes play a central role in the host response to Histoplasma capsulatum, little is known of the nature of Histoplasma antigens recognized by these cells in vitro. Employing a murine T-cell line and two clones that are reactive with histoplasmin, we examined whether activation of T cells by histoplasmin required the presence of carbohydrate or protein moieties. The approach taken was to modify carbohydrate or protein molecules in histoplasmin by chemical or enzymatic digestion or by lectin adsorption. In parallel, antigen was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis to correlate alterations in functional activity with changes in the electrophoretic appearance of histoplasmin. Treatment of histoplasmin with periodate (0.1 M, 0.05 M, and 0.01 M) or with the endoglycosidases N-glycanase and endoglycosidase H sharply diminished the capacity of histoplasmin to trigger responses by T cells. Reactivity of T cells to histoplasmin that had been adsorbed with lectins binding mannose, glucose, or galactose was reduced by greater than 70%; conversely, the responses by T cells to antigen that had been adsorbed with lectins specific for fucose, N-acetylgalactosamine, or N-acetylglucosamine ranged from 82 to 91% of that to control antigen. Proliferative responses by T cells to histoplasmin that had been digested with chymotrypsin, protease, or trypsin were 2 to 43% of control values. The electrophoretic appearance of histoplasmin was modified by some but not all of the treatments. Partially purified H and M antigens triggered proliferation of T cells. Thus, both carbohydrates and proteins must be present to induce optimal responses by T cells. A portion of the carbohydrates is N linked to proteins, and alpha-D-mannose (or alpha-D-glucose) and beta-D-galactose are the sugar ligands of carbohydrate-containing antigens.
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PMID:Characterization of antigenic determinants in histoplasmin that stimulate Histoplasma capsulatum-reactive T cells in vitro. 245 54

Bordetella pertussis, the pathogen responsible for whooping cough, releases a soluble calmodulin-sensitive adenylate cyclase into its culture medium. Several investigators have shown that the partially purified adenylate cyclase is capable of entering animal cells and elevating intracellular cAMP levels [Confer, D. L., & Eaton, J. W. (1982) Science 217, 948-950; Shattuck, R. L., & Storm, D. R. (1985) Biochemistry 24,6323-6328]. However, the mechanism for entry of the catalytic subunit of the adenylate cyclase into animal cells is unknown. Recently, it was determined that the purified catalytic subunit of the enzyme is unable to enter animal cells [Masure, H. R., Oldenburg, D. J., Donovan, M. G., Shattuck, R. L., & Storm, D. R. (1988) J. Biol. Chem. 263, 6933-6940]. On the basis of these data and other observations, we hypothesized that the culture medium of B. pertussis contains one or more additional polypeptides which facilitate entry of the adenylate cyclase catalytic subunit into animal cells. In this study, we report that a cell-invasive preparation of B. pertussis adenylate cyclase was rendered noninvasive after passage through a wheat germ lectin-agarose column. A fraction was eluted from the wheat germ lectin-agarose column with N-acetyl-D-glucosamine. This fraction, when combined with the noninvasive adenylate cyclase, was able to restore the ability of the adenylate cyclase preparation to enter neuroblastoma cells and increase intracellular cAMP levels. Furthermore, the fraction eluted from the wheat germ lectin-agarose column was found to be trypsin and chymotrypsin sensitive, suggesting that this material was proteinaceous.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Isolation of a protein fraction from Bordetella pertussis that facilitates entry of the calmodulin-sensitive adenylate cyclase into animal cells. 255 96

Optimum conditions were determined for solubilizing cell membrane receptors for binding measles virus (MV). Evidence for specific receptors was shown from the saturability of MV binding to intact Vero cells or African Green Monkey erythrocytes (MRBCs). Receptors, solubilized from Vero cells and MRBC with 1.5% octyl glucoside, inhibited MV attachment, infectivity, and hemagglutination activities. Extracts from chicken erythrocytes, which did not bind MV, were inactive in all assays. MV binding activity in Vero or MRBC extracts was stable to heating (100 degrees, 10 min) or neuraminidase treatment, but was inactivated by a range of proteases, including chymotrypsin, and bound to lentil and pea lectin agaroses, to indicate a glycoprotein component.
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PMID:Characterization of octyl glucoside-solubilized cell membrane receptors for binding measles virus. 267 66

The dietary implications of feeding sub-lethal doses of extracted and purified lectin from lima bean were assessed in weanling rats using changes in relative organ weights, pancreatic and intestinal trypsin and chymotrypsin activities as the response indices. Liver weights decreased significantly (p less than 0.05) while the heart showed a slight but non-significant increase in response to dietary lectin levels. The kidneys, pancreas and spleen were not significantly affected by dietary lectin. Although the activities of the pancreatic enzymes tended, for the most part, to decrease with increasing dietary lectin, such decreases were not significant when compared with the control. Intestinal trypsin and chymotrypsin activities were significantly (p less than 0.05) decreased in the small intestine while the activity values in both the large intestine and caecum were relatively unaffected. Activities of both enzymes showed significant (p less than 0.05) negative quadratic relationship with dietary lectin levels in the small intestine as judged by the magnitude of the R2, coefficients of multiple determination, of 0.77 and 0.76 for trypsin and chymotrypsin respectively.
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PMID:Effect of dietary sub-lethal doses of lima bean lectin on relative organ weights, pancreatic and intestinal trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1) in the rat. 275 71

The heparin-binding lectin from human placenta is isolated on the basis of its tendency to form large aggregates by gel filtration and on the basis of its affinity for heparin by affinity chromatography. The purified lectin dissociates into up to four distinct polypeptides with molecular weight values of 14,400, 15,000, 16,200, and 16,700 and a single isoelectric point of 9.0. Molecular heterogeneity is not due to different degrees of glycosylation, as evidenced by gel electrophoretic analysis after extensive treatment with various endoglycosidases. Despite its similarities of affinity to heparin, molecular size, and isoelectric point to the basic fibroblast growth factor (bFGF), the comparatively high yield of the lectin (approximately 1.5 mg/100 g of placenta), the occurrence of proteolytic fragmentation in the presence of heparin, and the lack of homology to the amino-terminal sequence of the lectin argue against any notable relationship to bFGF. Most importantly, the lack of mitogenic activity in a commonly used bioassay with quiescent 3T3 fibroblasts rules out any FGF-like activity on cell proliferation. The heparin-binding lectin is thus clearly distinguishable from heparin-binding growth factors. By employing biotinylated heparin as labeled ligand to visualize and quantify heparin binding, hapten inhibition in a solid-phase assay reveals that except for heparin no other vertebrate glycosaminoglycan but the sulfated fucan fucoidan can effectively reduce the Ca2+-independent ligand binding. Proteolytic fragmentation by chymotrypsin in two independent assays demonstrates that a fragment of Mr 7800 still retains ability to bind heparin. The interaction of this lectin with naturally occurring heparin-like molecules may physiologically be involved in modulatory regulation of heparin-mediated processes.
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PMID:Heparin-binding lectin from human placenta: purification and partial molecular characterization and its relationship to basic fibroblast growth factors. 279 11

Immunoreactive PRL (IR-PRL) has been identified in many areas of the rat brain. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analyses we have recently shown that the primary IR-PRL protein in the rat brain has an apparent mol wt (Mr) of 24,000, which was identical to that of pituitary PRL. In these studies, brain and pituitary 24,000 Mr PRL were compared by peptide mapping and lectin chromatography. PRL-enriched fractions were prepared from the pituitary, hypothalamus, hippocampus, and pons-medulla and labeled with 125I. This material was further purified by immunoprecipitation, and immunopurified 24,000 Mr PRL was isolated by sodium dodecyl sulfate-gel electrophoresis. Cleavage of 125I-labeled 24,000 Mr IR-PRL prepared from the pituitary and the three brain regions with chymotrypsin resulted in identical peptide maps with two primary labeled peptide fragments (5,500 and 6,000 Mr), and approximately five less intense fragments. Similarly, trypsin cleavage of brain and pituitary 24,000 Mr IR-PRL resulted in the production of two major fragments (6,200, and 5,200 Mr), and three less intense fragments. Cleavage of the 24,000 Mr IR-PRL with Staphylococcus V8 protease resulted in identical fragment patterns with two primary peptide fragments (14,000 and 6,200 Mr). When the pituitary and brain 24,000 Mr PRL were applied to Concanavalin-A-Sepharose columns no 24,000 Mr PRL was absorbed. The similarity of the peptide fragments obtained from the cleavage of the 24,000 Mr IR-PRL from the brain and pituitary clearly indicate that the IR-PRL found in the brain has an amino acid sequence that shares a high degree of structural homology with pituitary PRL.
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PMID:Comparison of brain and pituitary immunoreactive prolactin by peptide mapping and lectin affinity chromatography. 279 95


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