Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.21.3 (deoxyribonuclease)
 1,528 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protease-free bovine pancreatic deoxyribonuclease (DNase) (1.6 X 10(-4) mmol) was thiolated on the NH2 groups with N-acetyl-DL-homocysteine thiolactone (2.4 X 10(-2) mmol) at pH 10.5 with imidazole (2.4 X 10(-2) mmol) as the catalyst in the presence of 4,4'-dithiodipyridine (4.2 X 10(-2) mmol). The product obtained after 16 h at 4 degrees C, 2-acetamido-4-(4'-dithiopyridyl)butyryl-DNase, isolated by gel filtration, contained an average of 0.87 +/- 0.13 mol of mixed disulfide per mol of DNase. Ribonuclease (RNase) was thiolated in a similar manner, but under N2 in the absence of 4,4'-dithiodipyridine. The protein N-acetylhomocysteinyl-RNase contained on the average 0.94 +/- 0.11 mol of sulfhydryl groups per mol of RNase. The coupling of RNase ot DNase was accomplished by thiol-disulfide interchange at pH 6.2 and 25 degrees C for 90 min. The hybrid enzyme (yield 25--33%, based upon the DNase derivative used) was freed from unreacted DNase, RNase, and homodimers by gel filtration, affinity chromatography, and salting-out chromatography. The purified enzyme contained one molecule each of DNase and RNase and hydrolyzed thymus deoxyribonucleic acid (DNA) and yeast or transfer ribonucleic acid (RNA) with 75 and 40% of the efficiencies, respectively, of the parent enzymes. The RNA strand of the hybrid substrate, phage f1 DNA-[3H]RNA, prepared from phage DNA with RNA polymerase, was hydrolyzed rapidly by the hybrid enzyme but was not hydrolyzed by RNase alone. A conjugate of the two enzymes offers the possibility in vivo of delivering two enzymes that differ in size, charge, and biological function to the same site at the same time.
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PMID:Preparation of the bifunctional enzyme ribonuclease-deoxyribonuclease by cross-linkage. 48 31

About 60 characteristics have been investigated in 7 hemolyzing and 12 nonhemolyzing strains of L. monocytogenes. From these investigations resulted inter alia that the organism grows well under strictly anaerobic conditions, esculin is split at 45 degrees C,NH3 is produced from peptone, but not from arginin, and H2S can be traced by sufficiently sensitive methods. All strains possess a lipase, muramidase, and deoxyribonuclease, the hemolytic ones only also a lecithinase. Besides, the hemolytic strains only dispose of experimental virulence and of a CAMP factor-like agent. The experimental animal of choice seems to be the conjunctivally infected guinea pig in which a generalized infection develops.
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PMID:[Some properties of carrier strains of Listeria monocytogenes (author's transl)]. 81 65

We have determined the nucleotide sequence of a 4.0-kilobase DNA fragment containing the genes of the PstI restriction-modification system. Two large open reading frames were identified within the sequence and were ascribed to the restriction enzyme and methylase by the analysis of a series of deletion mutants. The two genes are encoded on opposite DNA strands, and hence must be transcribed from separate promoters rather than as a polycistronic message. The sequence of the first 10 amino acids of the restriction endonuclease was determined by sequential Edman degradation of the purified protein, permitting the alignment of the polypeptide with the DNA sequence. The NH2 terminus of the modification enzyme was established by sequential Edman degradation of the protein synthesized in bacterial minicells with different radiolabeled amino acids. The initiation codons of the two genes are separated by 130 base pairs. The deduced amino acid sequences indicate that the restriction endonuclease contains 326 amino acids with a calculated Mr = 37,370; the modification enzyme is composed of 507 amino acids with a calculated Mr = 56,830. There is no significant homology between the two proteins at the level of the primary structure. Antibody raised against the purified restriction endonuclease did not immunoprecipitate the modification enzyme. The transcription initiation sites were mapped using mung bean nuclease. Both of the transcripts begin with adenosine. The initiation sites are separated by only 70 base pairs. This close proximity suggests that the promoters for the two divergent genes overlap. DNase I protection experiments show that Escherichia coli RNA polymerase has a higher affinity for the methylase promoter than for the restriction enzyme promoter.
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PMID:The organization and complete nucleotide sequence of the PstI restriction-modification system. 633 92

Young adult male Sprague-Dawley rats were given 30 mumol/kg body weight [14C]methylamine hydrochloride and 700 mumol/kg body weight sodium nitrite by oral gavage. DNA isolated from the stomach and from the first 15 cm of the small intestine was methylated, containing 7-methylguanine (7mG) at a level of one 7mG molecule per 5 X 10(6) and 1 X 10(7) nucleotides, respectively. No 7mG was found in the liver at a limit of detection of one 7mG molecule per 2 X 10(8) nucleotides. In a second experiment, the excised stomachs were incubated with deoxyribonuclease before the isolation of the DNA in order to degrade DNA in the lumen and in the uppermost lining cells. This treatment resulted in a 30% decrease in the yield of DNA and a 90% reduction in the level of 7mG formation. The results show that nitrosation of a primary alkylamine yields a precursor of an alkylating agent which has a long enough lifetime to diffuse towards and react with intracellular DNA. A correlation of DNA methylation in the stomach with the corresponding tumor formation by the methylating carcinogen N-methyl-N'-nitro-N-nitroso-guanidine was used to estimate the role of DNA damage resulting from endogenous nitrosation of dietary methylamine in man. It was concluded that the risk resulting from this single amine must be negligible but that a similar evaluation of other primary amines is required before the over-all role of primary amine nitrosation in the etiology of human gastric cancer can be assessed.
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PMID:Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite. 649 25

Isolated nuclei incubated with [14C]protein hydrolysate are shown to incorporate labelled amino acids into the acid-insoluble fraction. Purified chromatin and the complex of DNA with firmly bound proteins possess similar ability. The optimum pH of the reaction is 6.5-7.0, 2 mM MgCl2 stimulates incorporation, the temperature optimum is 37-40 degrees C. Chloramphenicol depresses incorporation by 70%, puromycin by 40%, cycloheximide does not affect the chromatin activity. Incorporation does not depend on the presence of ATP or GTP, and is substantially inhibited by deoxyribonuclease but not by ribonuclease treatment of chromatin or of the nuclei. Specific activity of firmly bound chromatin non-histone proteins is higher than that of labile bound ones; histones are not labelled. After pronase treatment of proteins radioactivity changes to an acid-soluble state. The molecular weight of isolated labelled polypeptides is about 6000 as shown by gel filtration and the analysis of NH2-terminal amino acids. Labelled polypeptides firmly bound to DNA consist of 7-10 amino acids. Specific activity of proteins firmly bound to DNA increases linearly with the time of incubation of chromatin with [14C]protein hydrolysate, the activity curve of labile bound non-histone proteins has a distinct sygmoid character. The polypeptide-synthesizing activity of rat liver chromatin increases between 9 h and 21 h after partial hepatectomy. Irradiation with 800 rads 30 min before the operation prevents activation of amino acid incorporation. From nine amino acids studied alanine, methionine, lysine, tyrosine and arginine are not incorporated in the system described. Glutamic acid is polymerized most effectively. Glutamine, asparagine and glycine are incorporated 7-8 times less. The data are given indicating that the incorporation is not random when an amino acid mixture is present. Preincubation of chromatin with NAD+ but not with its analogues increases the polypeptide-synthesizing activity of chromatin. The activation is prevented by thymidine and nicotinamide. Storage (18 h at 2-4 degrees C) brings about a complete loss of the polypeptide-synthesizing activity of chromatin. The ability of 'old' chromatin to incorporate amino acids can be restored by preincubating it with NAD+. Storage of chromatin in the presence of 5 mM adenosine 3',5'-monophosphate (cAMP) does not result in decrease of the polypeptide-synthesizing activity. It is assumed that poly-(ADP-ribose) is the energy source for amino acid activation in the system described.
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PMID:Polypeptide-synthesizing activity of eukaryotic chromatin. Properties, dependence on poly(ADP-ribose) and connection with the cell cycle. 737 37

The present work demonstrates a rapid, single-step and ultrasensitive label-free and signal-off electrochemical sensor for specific DNA detection with excellent discrimination ability for single-nucleotide polymorphisms, taking advantage of Exonuclease III (Exo III)-aided target recycling strategy to achieve signal amplification. Exo III has a specifical exo-deoxyribonuclease activity for duplex DNAs in the direction from 3' to 5' terminus, however its activity on the duplex DNAs with 3'-overhang and single-strand DNA is limited. In response to the specific features of Exo III, the proposed E-DNA sensor is designed such that, in the presence of target DNA, the electrode self-assembled signaling probe hybridizes with the target DNA to form a duplex in the form of a 3'-blunt end at signaling probe and a 3'-overhang end at target DNA. In this way, Exo III specifically recognizes this structure and selectively digests the signaling probe. As a result, the target DNA dissociates from the duplex and recycles to hybridize with a new signaling probe, leading to the digestion of a large amount of signaling probes gradually. A redox mediator, Ru(NH(3))(6)(3+) (RuHex) is employed to electrostatically adsorbed onto signaling probes, which is directly related to the amount and the length of the signaling probes remaining in the electrode, and provides a quantitative measure of sequence-specific DNA with the experimentally measured (not extrapolated) detection limit as low as 20 fM. Moreover, this E-DNA sensor has an excellent differentiation ability for single mismatches with fairly good stability.
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PMID:A label-free electrochemical DNA sensor based on exonuclease III-aided target recycling strategy for sequence-specific detection of femtomolar DNA. 2182 Aug 85