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)

Treatment of submitochondrial particles (ETP) with trypsin at 0 degrees destroyed NADPH leads to NAD (or 3-acetylpyridine adenine dinucleotide, AcPyAD) transhydrogenase activity. NADH oxidase activity was unaffected; NADPH oxidase and NADH leads to AcPyAD transhydrogenase activities were diminished by less than 10%. When ETP was incubated with trypsin at 30 degrees, NADPH leads to NAD transhydrogenase activity was rapidly lost, NADPH oxidase activity was slowly destroyed, but NADH oxidase activity remained intact. The reduction pattern by NADPH, NADPH + NAD, and NADH of chromophores absorbing at 475 minus 510 nm (flavin and iron-sulfur centers) in complex I (NADH-ubiquinone reductase) or ETP treated with trypsin at 0 degrees also indicated specific destruction of transhydrogenase activity. The sensitivity of the NADPH leads to NAD transhydrogenase reaction to trypsin suggested the involvement of susceptible arginyl residues in the enzyme. Arginyl residues are considered to be positively charged binding sites for anionic substrates and ligands in many enzymes. Treatment of ETP with the specific arginine-binding reagent, butanedione, inhibited transhydrogenation from NADPH leads to NAD (or AcPyAD). It had no effect on NADH oxidation, and inhibited NADPH oxidation and NADH leads to AcPyAD transhydrogenation by only 10 to 15% even after 30 to 60 min incubation of ETP with butanedione. The inhibition of NADPH leads to NAD transhydrogenation was diminished considerably when butanedione was added to ETP in the presence of NAD or NADP. When both NAD and NADP were present, the butanedione effect was completely abolished, thus suggesting the possible presence of arginyl residues at the nucleotide binding site of the NADPH leads to NAD transhydrogenase enzyme. Under conditions that transhydrogenation from NADPH to NAD was completely inhibited by trypsin or butanedione, NADPH oxidation rate was larger than or equal to 220 nmol min-1 mg-1 ETP protein at pH 6.0 and 30 degrees. The above results establish that in the respiratory chain of beef-heart mitochondria NADH oxidation, NADPH oxidation, and NADPH leads to NAD transhydrogenation are independent reactions.
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PMID:Oxidation of NADPH by submitochondrial particles from beef heart in complete absence of transhydrogenase activity from NADPH to NAD. 0 Mar 95

A cytochemical method is presented for the demonstration of proteases in human polymorphonuclear (PMN) neutrophils on fixed blood smears. This new technique is based on solubilization of proteases from PMN neutrophils by incubation with 0.25 M NaCl in borate buffer at pH 8.5 which leads to degradation of erythrocytes and plasma in a disclike zone (halo) around centrally situated PMN neutrophils, an effect that is visualized by staining smears using a modified colloidal iron reaction. Halo formation is inhibited by trypsin inhibitors of soya-bean as well as of chicken egg white mucoid and by phenylmethyl-sulfonylfluoride.
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PMID:On testing the activity of proteases from human polymorphonuclear neutrophils on blood smears. 3 Aug

The specific granules are argentafugic when ultrathin sections of Araldite-embedded atria are stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery. The entire core of the atrial specific granules is moderately positive after ultrathin sections of glutaraldehyde-fixed, glycol methacrylate- (GMA-) embedded atria are stained with phosphotungstic acid at a low pH. A similar reaction is shown by the cell coat, intercalated discs, residual bodies (C-granules), and Z-discs, as well as by a very small portion of the Golgi complex. Analogous results are obtained with semithin sections of GMA- embedded atria stained according to the periodic acid-Schiff (PAS) technique. In ultrathin sections of GMA-embedded atria stained with dialyzed colloidal iron (DI), the cell coat of the cardiocytes is positive, unlike all the other cytoplasmic organelles. When ultrathin sections of GMA-embedded atria are incubated with proteolytic enzymes (pronase, pepsin, or trypsin), atrial specific granules and Z-bands and, to a much lesser degree, cell coat and sarcolemma are selectively digested. Proteins are also distinctly demonstrated in the paranuclear specific granules by a variety of histochemical techniques. These results indicate that atrial specific granules are rich in proteins and possess a weak complement of complex carbohydrates.
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PMID:Chemical nature of atrial specific granules. 5 70

The effect of the iron content of the medium on the yields of extracellular products by seven distinct strains of Pseudomonas aeruginosa was examined. All strains showed at least an 85% decrease in toxin A yields when grown in medium containing 5.0 mug of iron per ml (high iron) as compared to 0.05 mug/ml (low iron), whereas bacterial growth increased approximately twofold. During the course of examining extracellular products produced by P. aeruginosa, we found many strains that produced an extracellular factor which agglutinated erythrocytes. This hemagglutinin was nondialyzable, heat stable, and resistant to Pronase and trypsin. The effect of iron on extracellular yields of hemagglutinin was strain dependent; four of seven strains showed decreases in hemagglutinin yields in high-iron medium. Similarly, the effect of increasing the iron concentration of the growth medium on yields of total extracellular proteases or on elastase was strain dependent. The amount of total extracellular protein was decreased by at least 31% in the high-iron medium for all strains of P. aeruginosa examined. Detailed studies on one strain (WR-9) showed that, in the presence of increasing amounts of iron in the medium, the extracellular yields of toxin A, protease, and hemagglutinin were decreased in a similar manner. In addition, the kinetics of release of these extracellular products were similar at a given iron concentration. Thus it appears that the yields of other extracellular products of P. aeruginosa besides toxin A are influenced by the concentration of iron in the growth medium.
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PMID:Influence of iron on yields of extracellular products in Pseudomonas aeruginosa cultures. 10 50

The layer of mucosubstance that is associated with the free surface membranes of the pneumonocytes in the lungs of the toad Xenopus laevis and the lizard Lacerta viridis was demonstrated by electron microscopy using iron oxide stain. The form and staining reactions of the mucosubstance layer were similar in both animals. In electron micrographs the mucosubstance was represented by a band of densely stained material (25-50 nm thick) which coated the entire free surface of the pneumonocytes. It appeared to be firmly attached to the outer leaflet of the superficial plasma membrane. Short lengths of osmiophilic membranes, presumed to be fragments of pulmonary surfactant, were often observed lying free in the air spaces but they did not show any affinity for iron stain. Incubation of lung sections in a solution of neuraminidase produced a marked decrease in the intensity of the surface staining; no change was detected after incubation in trypsin, papain, hyaluronidase, N-acetyl cysteine, or phosphate buffer. It is, therefore, concluded that the pneumonocyte surface coat consists mainly of a sialomucin.
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PMID:The mucosubstance coating the pneumonocytes in the lungs of Xenopus laevis and Lacerta viridis. 16 63

1. It is confirmed that there are two e.p.r. (electron-paramagnetic-resonance) signals associated with fully loaded ovotransferrin, which has two iron-binding sites. 2. Through experiments in which either of the two sites of whole ovotransferrin is occupied, the other being empty, the first occupied site is shown to belong to the N-terminal region of the protein; the second occupied site is in the C-terminal region. 3. When the protein is cleaved with trypsin or subtilisin, the N-terminal fragments are spectroscopically similar to the monoferric ovotransferrin complexes in which the iron atom occupies the N-terminal or C-terminal site respectively. Each fragment displays the same two e.p.r. signals, though not in the same proportions. 4. Computer summations of the e.p.r. spectra confirm that there is no iron-iron interaction which affects the spin Hamiltonian parameters at the iron-binding sites.
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PMID:Electron-paramagnetic-resonance spectroscopy of iron-binding fragments of hen ovotransferrins. 17 91

Experiments demonstrating the existence of receptors for iron-saturated transferrin on both B and T lymphoblastoid cell lines of human origin are described. Binding of 125I-labeled transferrin is rapid, saturable and reversible. It can be specifically inhibited by unlabeled transferrin but not by other proteins. The number of receptors on T cell lines determined by Scatchard analysis is almost double the number on B cell lines but the binding affinities are equal. The putative transferrin receptor can be removed from the cell by the proteolytic enzymes papain and trypsin, and is re-expressed during overnight incubation at 37 degrees C. Resynthesis is inhibited by puromycin. The receptor can be solubilized by deoxycholate, and retains transferrin binding capacity when non-covalently attached to an amphipathic matrix consisting of deoxycholate-coupled poly(L-lysyl) Agarose.
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PMID:Transferrin receptors on human B and T lymphoblastoid cell lines. 21 39

The complete amino acid sequence of the mangano superoxide dismutase from Escherichia coli B has been deduced through characterization of peptides from cyanogen bromide, bromonitrophenylsulfenyl skatole, citraconylated tryptic, and succinylated tryptic digests of the intact polypeptide chain and through subfragmentation of selected peptides with chymotrypsin, thermolysin, trypsin, and Staphylococcus aureus V8 extracellular protease. No significant homology is detected on comparison with the sequence of the copper- and zinc-containing superoxide dismutase from bovine erythrocytes, indicating that the manganese-iron and the copper-zinc classes of dismutases arose from independent evolutionary ancestors, a proposal previously based solely on enzymological and NH2-terminal sequence data. The amino acid sequence listed below corresponds to a molecular weight of 22,900 and appears to be identical in each subunit polypeptide of the native enzyme dimer. formula: (see text).
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PMID:The amino acid sequence of mangano superoxide dismutase from Escherichia coli B. 36 8

The ability of lymphocytes to lyse human red cells coated with anti-D antibody was assessed by measuring 51 Cr release from labeled red cells incubated with peripheral blood leukocyte suspensions from 12 normal donors. Mixed mononuclear cell suspensions (containing monocytes and lymphocytes) from all donors produced lysis of sensitized red cells. Treatment with carbonyl iron reduced monocyte concentration to less than 1.2% in all donors, as measured by morphologic criteria, esterase staining and ingestion of latex particles. Lysis of red cells following monocyte depletion was markedly reduced in 8 of the 12 donors. Despite depletion of monocytes, unchanged or increased lysis was noticed with the leukocytes of the remaining 4 donors. This lysis was due to lymphocytes, not to residual monocytes. If target red cells were treated with papain or trypsin prior to sensitization, marked lysis occurred with lymphocytes of all donors, including those which did not lyse unmodified red cells. Direct cytolysis of sensitized red cells during contact with small lymphocytes was recorded using microcinematography, which confirmed the role of lymphocytes in mediating lysis. Lymphocyte-mediated lysis of red cells increased with mounting levels of antibody sensitization regardless to prior treatment with papain. Papain increased antibody coating per red cell, yet lysis per molecule of antibody bound was also increased. Lysis was inhibited by IgG1 and IgG3 in the fluid phase but not by IgG2 or IgG4. At an equivalent level of antibody sensitization lysis was augmented by concurrent coating of the red cells with C3b, C3d and/or C4b, though these components could not produce lysis in the absence of antibody coating.
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PMID:Quantitative evaluation of antibody-dependent lymphocyte-mediated lysis of human red cells. 53 2

The amino acid sequence of hemerythrin from the sipunculid worm, Themiste dyscritum, was determined by sequenator analyses of the S-pyridylethylated protein and fragments derived by further chemical and enzymatic cleavages. The fragments were obtained by cleavage of the intact protein with hydroxylamine, trypsin digestion of citraconylated intact protein, and subdigestion with Staphylococcal protease V8. The COOH-terminal sequence was determined using carboxypeptidases A and B and amino acid analyses. The polypeptide chain was found to contain 113 amino acids. Since heterogeneity was observed at no more than two positions in the amino acid sequence, the native octameric protein appears to be composed of identical subunits. By combining information derived from sequence analyses and x-ray crystallographic studies, it has been possible to identify amino acids responsible for the tertiary and quaternary structure of the protein as well as amino acids serving as iron ligands at the oxygen-binding site.
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PMID:Amino acid sequence of hemerythrin from Themiste dyscritum. 67 Feb 24


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