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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuron-specific enolase and creatine phosphokinase were found, by 2-dimensional gel analysis, in rat brain synaptic plasma membranes (SPM). The identity of these enzymes was confirmed by comigration with purified rat brain NSE and CPK and by peptide analysis. The specific enzymatic activities of enolase and creatine phosphokinase, as well as of pyruvate kinase, also present on the membranes, were comparable to those in the homogenates when these three enzymes were fully activated. In the SPM all three enzymes, particularly enolase, were partially cryptic in that enzymatic activities were very low unless the membranes were treated with Triton X-100. They were resistant to both low-salt and high-salt extraction and to trypsin, except when Triton X-100 was present. These results suggest that the enzymes are tightly bound protein components of the membrane and that they may constitute an assembly capable of generating ATP.
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PMID:Neurone-specific enolase and creatine phosphokinase are protein components of rat brain synaptic plasma membranes. 661 55

The subcellular localization of enkephalins was studied in the bovine adrenal medulla. In the adrenal medulla enkephalins (Met-enkephalin, Leu-enkephalin, Met-enkephalin-Arg6-Phe7 and Met-enkephalin-Arg6-Gly7-Leu8) are found free and in the form of cryptic peptides included in larger precursors. Total Met-enkephalin immunoreactivity, which includes free and cryptic peptides, was determined after a sequential enzymatic treatment with trypsin and carboxypeptidase B. Total Met-enkephalin immunoreactivity, dopamine beta-hydroxylase and catecholamines were found to have a parallel distribution in the various subcellular fractions. The bulk of the total Met-enkephalin immunoreactivity (42%) was recovered in the large granule fraction. The large granule fraction also contained 38% of the total dopamine beta-hydroxylase activity, and 42% of the total catecholamines. Enkephalins are thus concentrated in the chromaffin granules. Chromaffin granules were also separated according to the method of Terland & coworkers into two fractions: one containing the dense noradrenergic vesicles and the other containing lighter adrenergic vesicles. Total Met-enkephalin immunoreactivity was restricted to the fractions containing the lighter adrenergic vesicles. In these fractions the molar ratio of adrenaline to total Met-enkephalin immunoreactivity was 97. This study is in accord with immunocytochemical observations which have indicated that enkephalins are located in adrenergic and not in the noradrenergic cells in the bovine adrenal medulla.
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PMID:Enkephalins are associated with adrenergic granules in bovine adrenal medulla. 664 23

A gram-positive, nonsporulating, microaerophilic rod that had two colonial variants was obtained during a study in which anaerobic bacteria were isolated from murine gastrointestinal tracts and screened for cryptic plasmids. The rod (both colonial variants) was identified as a Lactobacillus sp. (strain 100-37) by selective media, gas chromatography, and biochemical tests. In monoassociated, ex-germfree mice, the bacterium colonized the gastrointestinal tract and formed a thick, continuous layer on the keratinized squamous epithelium of the nonsecreting portion of the stomach. When lysate preparations of both colonial variants were electrophoresed in agarose gels, two bands which stained with ethidium bromide were detected with each lysate. When the DNA preparations were exposed to UV light, the lower ethidium bromide band gradually disappeared while the top band became either broader or more intense. The approximate size of the lower band was 2.2 megadaltons, as determined by comparison with plasmid molecular weight standards. In a search for phenotypes which could be encoded by the cryptic 2.2-megadalton plasmid, we detected an antagonistic activity toward an obligate anaerobe isolated from mouse feces, Clostridium ramosum H1. The antagonistic factor was precipitated with (NH4)2SO4 (70% saturation) from supernatant solutions of broth cultures of strain 100-37. The factor was not inducible with mitomycin C or UV light, but was stable in flowing steam for up to 50 min, and in buffers of pHs over a range of 1.6 to 6.8. It was nondialyzable and inactivated by trypsin and papain.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of Lactobacillus sp. strain 100-37 from the murine gastrointestinal tract: ecology, plasmid content, and antagonistic activity toward Clostridium ramosum H1. 665 Dec 95

Line 10 guinea pig carcinoma cells cultured in serum-free medium for 4 hr elaborate plasminogen activator (PA) activity that remained in the supernatant after ultracentrifugation (100,000 X g, 90 min). PA activity in line 10 conditioned medium occurred in both active and cryptic forms. The vast majority of active PA adsorbed to lysine-Sepharose and could be eluted at low pH as several activities that electrophoresed in the Mr 50,000 to 80,000 range on nonreduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A small amount of active PA, running in the Mr 50,000 to 60,000 region, and cryptic PA did not adhere to lysine-Sepharose. Treatment of lysine-Sepharose-nonadherent fractions with catalytic amounts of plasmin or trypsin induced substantial new PA activity that adsorbed to lysine-Sepharose, bound [3H]diisopropylfluorophosphate, and that electrophoresed as several bands of activity with molecular weights from 50,000 to greater than 100,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Of additional interest, the amount of active PA measured in conditioned medium was substantially increased when certain protease inhibitors, tranexamic acid, epsilon-aminocaproic acid, or Trasylol, were included during culture.
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PMID:Cryptic and active plasminogen activators secreted by line 10 tumor cells in culture. 668 8

Extensive immunohistochemical and thin-layer chromatogram-immunostain analyses were carried out to establish whether asialo GM1, a glycolipid which contains binding sites for Pseudomonas aeruginosa, is present in corneal epithelium. The data suggest that rabbit corneal epithelium does not contain detectable levels of asialo GM1 even after corneas are scarified and incubated with trypsin, P. aeruginosa, or P. aeruginosa exoproducts to expose potential cryptic sites. Preliminary immunohistochemical analyses indicated that asialo GM1 is also not found in human corneas.
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PMID:Pseudomonas aeruginosa infection of the cornea and asialo GM1. 764 20

The multicatalytic proteinase complex (MPC) or proteasome is a multimeric, high-molecular-weight (700,000), extralysosomal proteolytic enzyme found in eukaryotes and in archaebacteria. Its multiple catalytic sites grant it a broad cleavage specificity toward short peptides and protein substrates. The pH optima of the catalytic activities of MPC are in the neutral or slightly alkaline range. We present here evidence for cryptic catalytic components of MPC optimally active at an acidic pH. Studies with a hydrophobic fluorescent probe provide direct evidence for conformational changes brought about by exposing the complex to an acidic environment. One of the newly described components, designated "acidic chymotrypsin-like activity," cleaves the Leu-2-naphthylamide bond in the substrate Boc-Val-Glu-Ala-Leu-2-naphythylamide. Compared with the classical "neutral" chymotrypsin-like activity defined by cleavage of the Leu-p-nitroanilide bond in Z-Gly-Gly-Leu-p-nitroanilide, the newly described component is not inhibited by monovalent cations and is less sensitive to the peptidyl aldehyde Z-Gly-Gly-leucinal, an inhibitor of the neutral chymotrypsin-like activity. In addition, we describe the properties of a novel potent peptidyl aldehyde, Z-Ile-Glu(OtBu)-Ala-leucinal, which is an inhibitor of both the acidic and neutral chymotrypsin-like activities of MPC, with IC50 values of 0.25 and 6.5 microM, respectively. In the presence of 65 microM of the newly synthesized peptidyl aldehyde, other MPC components such as the trypsin-like and peptidyl-glutamyl peptide hydrolyzing activities were decreased only by 14 and 9%, respectively. The hydrophobicity, potency, and specificity of Z-Ile-Glu(OtBu)-Ala-leucinal toward the chymotrypsin-like activities of the complex make it a valuable pharmacological tool with which to investigate the physiological roles of MPC.
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PMID:A novel chymotrypsin-like component of the multicatalytic proteinase complex optimally active at acidic pH. 787 5

Skin fibroblasts from a proband with mild osteogenesis imperfecta (type I) synthesized normal pro alpha 2(I) chains and shortened pro alpha 2(I) chains of type-I procollagen. The type-I collagen that contained the shortened alpha 2(I) chains was thermally unstable in that it was cleaved at 30 degrees C by a mixture of trypsin and chymotrypsin. The mutation generating the shortened pro alpha 2(I) chains was shown to be a deletion of 19 base pairs from +4 to +22 of intron 13 of the COL1A2 gene by sequencing of genomic DNA and allele-specific oligonucleotide hybridization. The same mutation was found in the proband's affected father. Probe-protection experiments with S1 nuclease demonstrated that about 88% of the RNA transcripts from the mutated allele were spliced by exon skipping from exon 12 to exon 14 and that about 12% of the RNA transcripts were normally spliced. There was no evidence for use of cryptic splice sites, even though two cryptic splice sites had more favorable statistical scores and delta G degree 37 values than the new site that was created by the mutation and that was used for splicing of 12% of the transcripts into a normal mRNA. Comparison of the results with observations on 17 previously reported mutations that produced in-frame deletions of amino acids from the triple-helical domain of type-I collagen indicated that deletions in the N-terminal half of the alpha 2(I) chain tended to produce milder phenotypes than similar deletions elsewhere in the alpha 1(I) or alpha 2(I) chains.
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PMID:Deletion of 19 base pairs in intron 13 of the gene for the pro alpha 2(I) chain of type-I procollagen (COL1A2) causes exon skipping in a proband with type-I osteogenesis imperfecta. 791 44

Up to four morphologically distinct types of cross-link are found between the stereocilia in the hair bundles of avian hair cells. These links are involved in mechanotransduction, force transmission across the bundle, and maintenance of hair bundle structure. They appear to be specialisations of the cell coat, but very little is known about their molecular composition. Chick inner ear tissues were therefore screened with a number of different lectins to find markers for specialisations of the hair bundle surface. One lectin, peanut agglutinin (PNA), which recognises the dissacharide Gal beta 1-3GalNAc, was found to be a fairly selective marker for vestibular hair bundles, but it does not stain the stereocilia of auditory hair cells. The staining patterns observed with PNA in the vestibular system closely resemble those seen with a monoclonal antibody (mab) directed against a 275 kD component of the hair cell's apical surface known as the hair-cell antigen (HCA). However, unlike PNA, the mab recognises both vestibular and auditory hair cells. A detailed comparison of the fluorescence staining patterns observed with PNA and the anti-HCA mab indicates that binding sites for both ligands spatially codistribute on the surface of vestibular hair cells. The lectin and the anti-HCA mab binding sites are both sensitive to trypsin treatment, and, with sections of the vestibular system, PNA pretreatment blocks subsequent anti-HCA mab staining. Immunoelectron microscopy of vestibular hair bundles shows that PNA and the anti-HCA mab both label a type of cross-link known as the shaft connector. This link type is present on both auditory and vestibular hair bundles but reacts with PNA only in the vestibular system. The lectin jacalin, which has greater specificity for Gal beta 1-3GalNAc than does PNA, also only labels vestibular and not auditory hair bundles. Although terminal sialic acid residues can block both PNA and jacalin binding, neuraminidase treatment does not unmask cryptic binding sites for these lectins on auditory hair cells but does reveal PNA and jacalin staining at a number of other locations in the inner ear. The results obtained with the lectins PNA and jacalin indicate that either the HCA or other components of the shaft links are differentially glycosylated in the vestibular and auditory epithelia of the bird. The functional significance for such a difference in glycosylation remains to be determined, but auditory and vestibular hair cells operate over different frequency ranges, and variations in glycosylation might confer different micromechanical properties on the hair bundles in these two systems.
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PMID:Differential glycosylation of auditory and vestibular hair bundle proteins revealed by peanut agglutinin. 792 1

Murine monoclonal antibodies (Mabs) were produced by vaccination of Balb/c mice with live Plasmodium falciparum-infected red cells (iRBC). The iRBC Mabs recognized altered forms of the human erythrocyte membrane protein band 3; however, these Mabs did not recognize the band 3 molecule in uninfected or ring-infected red cells. The location of epitopes was determined by studying the binding of the iRBC Mabs after selective proteolysis of band 3 as well as by the reactivity of these Mabs to synthetic peptides that corresponded to putative exofacial regions of band 3. Treatment of uninfected red cell membranes with trypsin under low ionic strength conditions resulted in exposure of cryptic epitopes of band 3 which were recognized by the iRBC Mabs. Several of the anti-iRBC Mabs (two of which were described previously) inhibited the in vitro adherence of infected erythrocytes to C32 amelanotic melanoma cells. A mouse polyclonal serum against a synthetic peptide based on an amino acid sequence motif of band 3 reacted (by immunostaining) only with the surface of iRBC and blocked adhesion. Thus, it appears that cryptic residues of the band 3 protein become exposed upon parasitization, and their presence contributes to the increased adhesiveness of the P. falciparum-infected red cell.
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PMID:Cytoadherence-related neoantigens on Plasmodium falciparum (human malaria)-infected human erythrocytes result from the exposure of normally cryptic regions of the band 3 protein. 802 54

Mitogen activation of resting lymphocytes induces expression of high affinity insulin receptors on the plasma membrane. The mechanism underlying this effect on insulin receptor expression was examined by comparing levels of insulin receptor mRNA and protein in resting and mitogen-activated rodent lymphocytes. Analysis of RNA levels indicated that resting and concanavalin A-activated lymphocytes contained equivalent amounts of insulin receptor mRNA with predominant transcripts of 7.9 and 9.5 kilobases. Although little or no insulin binding was detectable on intact resting lymphocytes, detergent solubilization of these cells resulted in the appearance of readily detectable insulin binding activity that could be immunoprecipitated with anti-insulin receptor antibodies. Detergent-solubilized resting and mitogen-activated lymphocytes expressed equivalent amounts of insulin receptors that bound insulin with similar affinity (KD = 90 pM) and migrated on reduced SDS-polyacrylamide gels with apparent masses of approximately 130 and approximately 95 kDa. Insulin receptors from resting lymphocytes appeared to be associated with the plasma membrane since 125I labeling of intact lymphocytes radiolabeled the insulin receptor, insulin binding activity was detected in membrane fractions of hypotonically lysed cells, and trypsin treatment of intact cells destroyed > 90% of the insulin binding activity in detergent extracts. These results suggest that resting lymphocytes express insulin receptor mRNA and protein and that mitogen activation exposes cryptic insulin receptors present in the plasma membrane of resting lymphocytes.
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PMID:Mitogen activation of resting lymphocytes exposes cryptic insulin receptors. 844 Jul 5


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