Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

T4 endonuclease V catalyzes the hydrolysis of the glycosyl bond of a thymine dimer in a DNA duplex and the cleavage of the 3'-phosphate by beta-elimination. We have previously identified a catalytic site for the first reaction (pyrimidine dimer-glycosylase activity) by systematic mutagenesis (Doi et al. Proc. Natl. Acad. Sci. USA 1992 in press) and by x-ray crystallography (Morikawa et al. Science, 256: 523-526, 1992). The results showed that replacement of Glu23 with either glutamine or aspartic acid completely abolished the glycosylase activity. We describe the investigation of the second reaction (apurinic/apyrimidinic endonuclease activity), using twenty two mutants of T4 endonuclease V plus a DNA mini duplex containing an abasic site. Replacement of Glu23 by glutamine abolished the second reaction, but replacement with aspartic acid did not. The pH optima of the mutant (23 Asp) and the wild type were found to be 5.0 and 5.5, respectively. We conclude that the carboxylate anion in position 23 may act as a general base in the beta-elimination reaction of the endonuclease.
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PMID:Participation of glutamic acid 23 of T4 endonuclease V in the beta-elimination reaction of an abasic site in a synthetic duplex DNA. 135 29

Cell walls were isolated by mechanical disruption of mid-log phase cells of Bacillus stearothermophilus NCA 1503-4R grown in Trypticase-yeast extract-fructose medium at 55 C. The cell walls were purified by treatment with sodium dodecyl sulfate (SDS) and incubation with deoxyribonuclease and trypsin. The cell wall peptidoglycan contained glucosamine, muramic acid, alpha, epsilon-diaminopimelic acid, and glutamic acid. Low amounts of glycine, galactosamine, serine, aspartic acid, lysine, and valine were also present. The relative mole ratios of glutamic acid-alpha, epsilon-diaminopimelic acid-glycine-alanine were 1.00:1.26:0.08:1.55. The cell walls were free from ribonucleic acid and deoxyribonucleic acid and contained less than 0.2% chloroform-methanol extractable lipid and 0.09 mumole of phosphorus per mg of cell wall. Teichoic acid was not detected in the cell walls of this organism. Cell walls isolated without treatment with SDS contained 7.5% chloroform-methanol extractable lipid, 0.24 mumole of phosphorus per mg of cell wall, and relatively high concentrations of all amino acids. These results suggest that the extracted lipid is not a cell wall component per se, but a contaminant from the lipoprotein cell membrane.
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PMID:Chemical composition of the cell walls of Bacillus stearothermophilus. 603 16

Syringacin 4-A, a bacteriocin produced by Pseudomonas syrinagae 4-A, was obtained by induction with ultraviolet irradiation or mitomycin C. Approximately 1,000-fold purification of the bacteriocin was achieved by manganous chloride precipitation, differential centrifugation, and chromatography on hydroxyapatite columns. The purified syngacin was homogeneous on hydroxyapatite columns and sucrose density gradients; it also sedimented as a single entity in the analytical ultracentrifuge. The buoyant density of purified syringacin in cesium chloride was 1.294 g/ml. The sedimentation coefficient was calculated as 120S, and the diffusion coefficient was 6.49 x 10(-8) cm(2)/s. The molecular weight was calculated as 1.6 x 10(7) from physical data and 1.7 x 10(7) from biological data. The syringacin was composed of about 88.4% protein, 8.5% arabinose, 2.2% galacturonic acid, and 0.7% glucosamine. Amino acid analysis indicated a predominance of leucine (12.1%), aspartic acid (12.2%), and glutamic acid (12.7%). The ultraviolet spectrum showed a maximum absorbance peak at 276 nm. The syringacin was heat and alcohol sensitive, but resistant to trypsin, chymotrypsin, carboxypeptidase, Pronase, protease, lysozyme, steapsin, deoxyribonuclease, and ribonuclease. Maximum pH stability was between 5 and 8. Crude bacteriocin was stable at room temperature for at least a year, and purified material was stable for at least 3 months at 4 C.
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PMID:Purification and characterization of syringacin 4-A, a bacteriocin from pseudomonas syringae 4-A. 1582 74