Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous 77Se NMR relaxation time studies established the utility of 77Se NMR spectroscopy in studying low molecular weight (less than 500) selenium-containing molecules. Since the spin rotation and chemical shift anisotrophy mechanisms contributed significantly to the 77Se spin-lattice relaxation in these compounds, it was questionable as to whether the latter mechanism would be efficient enough to enable 77Se resonances to be observed in a reasonable period in high molecular weight selenobiomolecules. Thus, to address this problem, disulfide bonds of ribonuclease-A and lysozyme were reductively cleaved under denaturing conditions, and the resulting 7-8 sulfhydryl groups were treated with a new sulfhydryl group reagent containing selenium, 6,6'-diselenobis(3-nitrobenzoic acid), to give proteins containing covalently attached selenium in the form of selenenyl sulfides. The observation of high resolution 77Se NMR spectra of these proteins under denaturing conditions was accomplished. Five to six 77Se NMR resonances, which fell in a chemical shift range of 14-15 ppm, were observed for each protein and are compared to the chemical shifts of several model selenenyl sulfides derived from cysteine.
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PMID:Demonstration of the feasibility of observing nuclear magnetic resonance signals of 77Se covalently attached to proteins. 627 74

Transition of bovine ribonuclease A from its monomeric to a dimeric form changes the pattern of enzymic activity response to ionic strength [Sorrentino, S., Carsana, A., Furia, A., Doskocil, J., and Libonati, M. (1980) Biochim. Biophys. Acta. 609, 40-52]. To see whether this phenomenon could be common to other enzyme-substrate systems, the action of various dimeric and monomeric enzymes (ox pancreas deoxyribonuclease, hog spleen acid deoxyribonuclease, bovine seminal ribonuclease, egg-white lysozyme, and papain) on polyelectrolytic substrates has been studied under different conditions of ionic strength. Dimerization of ox pancreas deoxyribonuclease, lysozyme and papain was obtained by cross-linkage with dimethyl suberimidate. The main results of the investigation, similar to those obtained with ribonuclease A, are the following. 1. Enzyme monomers and dimers show markedly different patterns of activity response to ionic strength at given pH values: the reactions catalyzed by monomeric enzymes are highly modulated by salt, whereas those catalyzed by dimeric enzymes are not. In particular, at the reaction optimum the monomeric form of an enzyme is significantly more active than the dimeric one. 2. The optimum of the reaction catalyzed by a dimeric enzyme is shifted to higher ionic strengths in comparison with that of the reaction catalyzed by a monomeric enzyme. A model is proposed that could explain these results on the basis of the influence of ionic strength on the intramolecular dynamics of the enzyme molecule and its non-specific interactions with polyelectrolytic substrates.
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PMID:Dimerization of deoxyribonuclease I, lysozyme and papain. Effects of ionic strength on enzymic activity. 628 87

Cross-linked dimers of ribonuclease, added at a concentration of 0.05 mg/ml to the culture medium of hepatoma (HTC) cells, were previously shown to inhibit intracellular degradation of peroxidase taken up by endocytosis. Intracellular localization showed that endocytosed peroxidase does not reach lysosomes in dimer-treated cells. The present study shows that preloading of lysosomes with fluorescent anti-peroxidase IgG, obtained by exposing HTC cells for 48 h to 0.1 mg of antibody/ml, restores intracellular degradation of endocytosed peroxidase. Moreover, accumulation of peroxidase into lysosomes, which no longer occurs in dimer-treated cells, occurs again under these conditions. We conclude that inhibition of transfer of peroxidase from phagosomes to lysosomes is most likely to be the alteration resulting from the exposure of the cells to ribonuclease dimer, rather than inhibition of fusion between phagosomes and lysosomes. The dimer of another basic protein, lysozyme added at a concentration of 0.2 mg/ml to the culture medium, is shown to induce the same type of effects as does the dimer of ribonuclease; the half-life of endocytosed peroxidase increased from 5 to 15 h after 2 h exposure of HTC cells to dimerized lysozyme. The effect of both dimers on intracellular protein processing can be reversed by addition of 100 mm-galactose to the culture medium, up to 5 h after pretreatment of the cells. The dimers of ribonuclease A or of lysozyme have thus probably the same mechanism of action. Evidence that the two dimers share the same binding sites on the cells is presented.
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PMID:Effects of cross-linked dimers of ribonuclease A or of lysozyme on the processing of endocytosed peroxidase by hepatoma cells. 628 32

A radiochemical method for the determination of the amino terminus on very small amounts (0.5-5 nmol) of protein is described. The high sensitivity of the method is achieved by using undiluted 1-fluoro-2,4-dinitro-[3,5-3H]benzene [( 3H]Dnp-F) as the labelling reagent under conditions in which a maximum amount of radioactive label is incorporated. Chemical homogeneity is achieved by reacting with excess unlabelled Dnp-F. High recovery is obtained by adding Dnp-albumin as carrier protein. A mixture of Dnp 14C-labelled amino acids is added prior to hydrolysis and identification of the amino terminus is made on the basis of the 3H/14C ratios of the separated Dnp-amino acids. The method was tested on insulin, pancreatic ribonuclease, and lysozyme which gave high 3H/14C ratios only in the expected amino-terminal amino acids. Application to multiple forms of poly(C)-avid ribonuclease gave only amino-terminal lysine. Two of four putative isozymes of 17 beta-hydroxysteroid dehydrogenase had serine as the amino terminus while the other two had aspartic acid or asparagine.
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PMID:A highly sensitive method for identification of amino termini of proteins: application to multiple forms of poly(C)-avid ribonuclease and 17 beta-hydroxysteroid dehydrogenase. 630 40

Immunochemical techniques with enzymes as the antigen have grown in frequency during the last few years. These techniques have allowed evaluation of enzymes in the presence of endogenous inhibitors. Among those enzymes measured by immunochemical techniques and which have found diagnostic application, mention will be made of alkaline phosphatase (with particular reference to the intestinal, placental, and Regan isoenzymes), lactate dehydrogenase (in which renewed interest has developed due to techniques for specifically measuring the LD-1 isoenzyme), aspartate aminotransferase (of which the cytosolic and mitochondrial forms can now be independently measured by immunochemical techniques), acid phosphatase (for which a specific immunochemical assay for the prostatic enzyme has been widely introduced in diagnostic laboratories), and creatine kinase (for which a variety of immunochemical techniques to measure the M- and B-subunits are now part of standard laboratory assays). Other enzymes which will be discussed in this review include phosphohexose isomerase, amylase, ribonuclease, and lysozyme (muramidase). Finally, the use of enzymes, particularly asparaginase, in the chemotherapy of cancer will be outlined.
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PMID:Immunoassay of enzymes--an overview. 634 26

An extracellular bactericidal substance was isolated from the supernatant of Streptococcus mutans Rm-10 culture fluid and partially purified with 60% ammonium sulfate precipitation, differential centrifugation, and gel filtration on Sephadex G-200. There was a good correlation of the sensitivity profiles of indicator strains whether assayed on solid medium or with purified material from cell-free culture fluid, indicating that the same inhibitory substance is produced on solid medium and in broth. Vapor from organic solvents such as chloroform, acetone, ethanol, and ether as well as heat treatment at 100 degrees C for 30 min had little effect on the bactericidal factor. It was sensitive to trypsin and pronase and resistant to deoxyribonuclease, ribonuclease, lysozyme, and phospholipase C. The inhibitor was not infective, and electron microscopic studies failed to reveal phage or phage-like particles in concentrated solutions of the bactericidal material. The results indicate that the extracellular bactericidal substance is indeed a bacteriocin. Activity in broth cultures reached a maximum only after exponential growth had ceased. It was active against other streptococcal strains as well as strains of Actinomyces naeslundii, A. viscosus, Bacillus subtilis and Staphylococcus aureus, but not against strains of Fusobacterium nucleatum and Escherichia coli.
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PMID:Isolation, partial purification and preliminary characterization of a bacteriocin from Streptococcus mutans Rm-10. 641 23

Pyridine borane has been reported as a superior reagent over a wide pH range, 5-9, for the reductive methylation of amino groups of proteins with formaldehyde [J. C. Cabacungan , A. I. Ahmed , and R. E. Feeney (1982) Anal. Biochem. 124, 272-278]. It has also been reported to reduce tryptophan to dihydrotryptophan and to inactivate lysozyme in trifluoroacetic acid [M. Kurata , Y. Kikugawa , T. Kuwae , I. Koyama , and T. Takagi (1980) Chem. Pharm . Bull 28, 2274-2275]. In the present study the specificity of pyridine borane for the two different modifications under different reaction conditions has been demonstrated, and extended to the application to the synthesis of protein containing reductively attached carbohydrates. In the acid reduction, pyridine borane selectively reduced all six tryptophans in lysozyme to dihydrotryptophan while all other amino acids remained intact. On similar treatment no cleavage of the carbohydrate moiety from chicken ovomucoid, and no losses of activity of ovomucoid or ribonuclease, two proteins devoid of tryptophan, were observed. Nearly complete methylation of the lysines of lysozyme, chicken ovomucoid, and ribonuclease was achieved with formaldehyde at pH 7.0 after 2 h at room temperature, with the retention of full activity of the protein without any destruction of tryptophan. The same chemistry was applied to covalently attach glucose and lactose to bovine serum albumin. Parameters, including pH, temperature, and methanol, that affect the reactions were investigated. Incremental additions of pyridine borane during the course of the reactions increased the rate of modification. The covalent attachment of sugar to the epsilon-amino group of lysine was demonstrated by the synthesis of N-alpha- acetylglucitollysine and comparison with acid hydrolysates of the bovine serum albumin-sugar derivatives.
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PMID:Pyridine borane as a reducing agent for proteins. 643 Jan 22

In a study of factors that influence the remaining secondary structure of reduced chicken eggwhite lysozyme, N-acetyl-D-glucosamine (NAG) and N,N'-diacetylchitobiose (di-NAG) were found to alter the circular dichroic (CD) spectrum of the reduced protein and its carboxymethyl derivative (Cml). Thus, negative ellipticities in the far u.v. were greater in the presence of the analogs, with NAG being the more effective. For Cml, curve fitting analysis of the CD data indicated an increased helical content in the presence of NAG by an average of 3% of the chain length, while beta-structure decreased by an equivalent amount. Other compounds structurally related to NAG produced no similar effects on the CD spectrum of Cml, nor were comparable effects of NAG in evidence on the Cm reduced derivatives of ribonuclease, chymotrypsin, wheat germ agglutinin, or alpha-lactalbumin. The effect therefore appears specific between NAG and Cml. Conversion of the tryptophan residue at Position 62 of Cml to the oxindolealanyl derivative prevented these effects of NAG, and this residue may therefore participate in the interaction. During a 4-day incubation at room temperature, the analog preserved the CD spectrum of Cml as well as its concentration. This effect was nearly specific when compared with other Cm reduced proteins and with other carbohydrates. Only one, N-acetyl mannosamine, was effective in preserving the concentration of Cml, but not the CD spectrum. Since D-glucosamine was entirely without effect on either the CD spectrum of Cml or on its change during incubation, the acetyl group appears essential for the NAG-Cml interaction. The specificity between NAG and Cml is tentatively accounted for in terms of interactions with the primary structure, rather than with the remaining secondary structure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evidence for interaction of substrate analogs with chicken eggwhite lysozyme after exhaustive reduction of disulfide bonds. 651 17

Six cationic protein bands were identified in extracts of both normal bovine blood neutrophils and their granules subjected to polyacrylamide disc gel electrophoresis. Band 1, the most cationic protein, was as positively charged as crystalline egg white lysozyme, and band 2 was as positively charged as ribonuclease. Antibacterial activity of various leukocyte fractions and cationic proteins was determined in vitro for Enterobacter aerogenes strain 2412-2. Antibacterial activity of various preparations was proportional to amount of test material present and varied inversely with number of bacteria in the test system. Comparative evaluations revealed that the neutrophil granule fraction had greater antibacterial activity than the whole cell homogenate or individual cationic proteins. Among cationic proteins, band 1 had the highest antibacterial activity, band 2 had the lowest, and band 3 had intermediate antibacterial activity. Cationic protein bands 4, 5, and 6 exhibited growth stimulatory rather than a growth inhibitory activity.
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PMID:Antibacterial activity of bovine blood neutrophils and their cationic proteins. 688 71

Mouse myeloid leukemia M1 cells were induced to differentiate in vitro into macrophages and granulocytes by various inducers, including dexamethasone. Prostaglandin F2 alpha inhibited the inductions by dexamethasone of phagocytic and lysozyme activities in M1 cells. Prostaglandin F2 alpha stimulated the production of differentiation-inhibiting activity (I-activity) in M1 cells. I-activity production by prostaglandin F2 alpha was decreased by simultaneous treatment with actinomycin D (5 ng/ml) but not with 5-fluoro-2'-deoxyuridine (10 ng/ml). The I-activity was inactivated by heating (70 degrees, 20 min) or by treatment with trypsin but not with mixed glycosidases or ribonuclease, suggesting that I-activity was due to a proteinous substance(s). B-Type prostaglandins also stimulated I-activity production, whereas A-, E- and D-type ones did not. Induction of prostaglandin E2. Retinoic acid stimulated the synthesis and release of prostaglandin F2 alpha and production of I-activity in M1 cells. Indomethacin completely inhibited induction of I-activity by retinoic acid. On the basis of these results, the relationship between I-activity production and prostaglandin F2 alpha production is discussed.
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PMID:Mechanisms of inhibition of mouse myeloid leukemic cell differentiation by prostaglandin F2 alpha. 695 29


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