Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of binding of an antitumour drug cis-diamminedichloroplatinum(II) (cis-[Pt(NH3)2Cl2]) to DNA on cutting effectiveness of BamHI, EcoRI, and SalI restriction endonucleases was quantitatively determined. The platinum complex inhibits the cleavage of plasmid pHC624 DNA linearized by BglI restrictase. From the present results we conclude that the yield of restriction endonuclease cleavage is also lowered if the platinum complex is bound outside the recognition DNA sequence of these enzymes. We propose that the origin of platinum adducts on DNA outside the recognition sequence can decrease the yield of restriction enzyme cleavage via inducing a conformational perturbation in the recognition DNA sequence of these enzymes and also via inhibition of the linear diffusion of these enzymes on DNA.
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PMID:Cleavage by restriction enzymes of DNA modified with the antitumour drug cis-diamminedichloroplatinum(II). 133 50

Some properties of DNA condensed with spermidine have been compared with the properties of DNA condensed with Co3+(NH3)6 to determine whether condensation of DNA with these trivalent cations protects DNA against the action of DNase I and increases transcription and encapsulation of DNA into liposomes. It was shown that DNA condensed with Co3+(NH3)6 was resistant to the action of the endonuclease DNase I such as DNA condensed with spermidine was. However, DNA condensed with Co3+(NH3)6 was significantly less active in transcription with the E. coli RNA polymerase than DNA-spermidine condensed forms. In addition, it was demonstrated that both compacted forms of DNA were more efficiently encapsulated into neutral liposomes; however, negatively, charged liposomes were scarcely formed in the presence of DNA condensed with Co3+(NH3)6. These experiments and the well documented properties of polyamines increasing the resistance to radiations and hydrolysis of nucleic acids, as well as their biological activities, such as replication, transcription, and translation, together with the low concentration of Co3+ in the environment, lead us to propose spermidine as a plausible prebiotic DNA condensing agent rather than Co3+ and the basic proteins proposed by other authors. Then, we consider the possible role and relevance of the polyamine-nucleic acids complexes in the evolution of life.
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PMID:Possible prebiotic significance of polyamines in the condensation, protection, encapsulation, and biological properties of DNA. 166 78

Four closely-related cis-platinum (Pt) complexes of 4(5)-nitroimidazole have been examined with respect to properties of radiobiological interest, to test the hypothesis that targeting a nitroimidazole (NO2Im) to DNA could enhance its radiosensitizing ability: I [PtCl2(5-NO2Im)2]; II [PtCl2(4-NO2Im)2]; III [PtCl2(NH3)(5-NO2Im)]; IV [PtCl2(NH3)(4-NO2Im)]. The reduction potential was affected to the same extent on metal binding in all of the complexes (delta E1/2 = +200 mV, cf. ligand measured polographically). Higher sensitization by 5-NO2 complexes I, III (cf. II, IV) was found. Only the mono complexes III and IV bind to DNA (in an assay using inhibition of restriction endonuclease activity); these radiosensitize as well as, or better than, free ligand in hypoxic CHO cells, and better than the bis complexes (I and II). The toxicity of the mono complexes is higher than ligand, and parallels the binding (III, IV, mono bis analogues). The complexes are compared with 4-nitroimidazole complexes of ruthenium, with respect to toxicity, binding and radiosensitization.
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PMID:Radiosensitization by metal complexes of 4(5)-nitroimidazole. 197 Sep 96

Ornithine transcarbamylase (OTC) (EC 2.1.3.3) is an hepatic mitochondrial enzyme involved in the detoxication of ammonia; it catalyzes the second step of the urea cycle, and is X-linked in human beings. Deficiency of OTC results in ammonia intoxication and, often, in early infant death, especially in males. This report describes the use of a nearly full-length cloned human cDNA for OTC for Southern blot analysis of genomic DNA. The pattern of MspI, TaqI, HindIII and EcoRI restriction endonuclease sites from 28 control individuals of Chinese backgrounds is reported. A Southern blot by Msp I reveals invariant bands of 19.5, 5.2 and 1.9 kb respectively, as well as one set of polymorphic bands 6.6/6.2 kb. By TaqI, invariant bands are 4.8, 2.7, 1.9, 1.7 and 1.4 kb respectively, while polymorphic bands are found at 4.1/3.9 kb. By HindIII, 3.2 kb is invariant but 4.0/2.9 kb polymorphic. By EcoR I, invariant bands are 9.0, 3.6, 3.4 and 1.45 kb respectively, but 2.5 kb is polymorphic. Combined with study of the alteration of restriction sites in the informative pedigrees, this information is expected to allow accurate heterozygote detection and prenatal diagnosis of OTC deficiency.
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PMID:Restriction fragment length polymorphisms at the ornithine transcarbamylase locus in normal Chinese. 197 99

Deficiency of ornithine transcarbamylase (OTC; EC 2.1.3.3), a hepatic mitochondrial enzyme involved in the detoxification of ammonia, is a severe inborn error of metabolism. It is an X-linked disorder which results characteristically in ammonia intoxication, protein intolerance and mental retardation. Early death of affected hemizygous male infants is common, while clinical manifestations in heterozygous females are variable due to random X-chromosome inactivation. Prenatal diagnosis by amniocentesis has not been feasible because OTC is not expressed in amniocytes and because no unusual metabolites can be detected in amniotic fluid. Fetal liver biopsy has been performed for some families at risk, but the dangers inherent in this procedure severely limit its usefulness. In this report, we describe the use of a nearly full-length cloned human cDNA to begin to characterize normal and mutant human OTC genes. One of 15 affected males was found to have a partial deletion of the OTC gene. Two distinct restriction fragment length polymorphisms (RFLPs) were identified at the OTC locus using the restriction endonuclease MspI; 69% of women tested were heterozygous for one or both polymorphisms. Identification of these common polymorphisms makes it possible to offer prenatal diagnosis to a large fraction of obligate carriers and to provide information on carrier status to some females at risk.
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PMID:Gene deletion and restriction fragment length polymorphisms at the human ornithine transcarbamylase locus. 298 25

Ornithine transcarbamylase (OTC) (E.C.2.1.3.3) is an X-linked hepatic enzyme in the urea cycle necessary for ammonia detoxification. Deficiency of OTC results in neonatal hyperammonemia, coma, and death in childhood. Because fibroblasts do not express OTC, prenatal diagnosis in the past has required fetal liver biopsy. Using a complementary DNA (cDNA) for OTC for Southern blot analysis of genomic DNA, we have found probands with complete OTC deficiency from two unrelated families in whom the same TaqI restriction endonuclease site has been altered because of independent, but not necessarily identical, mutations in the OTC gene, suggesting that this site may be a relative hotspot for mutation at a location that is critical for normal gene function. This TaqI alteration has allowed the identification of the individual in each family in whom the mutation originated as well as the exclusion of a recurrence of OTC deficiency in a male fetus at risk for the disease. OTC deficiency joins the growing list of genetic disorders for which Southern blot analysis allows accurate heterozygote detection and prenatal diagnosis in conditions for which they were not previously available.
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PMID:New mutation and prenatal diagnosis in ornithine transcarbamylase deficiency. 300 7

The UvrB-DNA preincision complex is a key intermediate in the repair of damaged DNA by the UvrABC endonuclease from Escherichia coli. DNaseI footprinting of this complex on DNA with a cis-[Pt(NH3)2[d(GpG)-N7(1),N7(2)]] adduct provided global information on the protein binding site on this substrate [Visse, R., et al. (1991) J. Biol. Chem. 266, 7609-7617]. By applying a method developed by Fairall and Rhodes [Fairall, L., & Rhodes, D. (1992) Nucleic Acids Res. 20, 4727-4731], who have used the size and shape of DNasI for the interpretation of a footprint, we were able to define in more detail the region where UvrB-DNA interactions in the preincision complex occur. The potential interactions with phosphate groups could be reduced to less then 14 in the damaged and to 12 in the nondamaged strand. The main UvrB-DNA interactions seem restricted to the major groove on both sides of the lesion. As a consequence UvrB crosses the minor groove just downstream of the damage. Such a binding of UvrB orients the protein away from the damage. The more detailed interpretation of UvrB-DNA interactions was supported by methylation protection experiments. The structure of the DNA in the preincision complex formed on cis-[Pt(NH3)2[GpG-N7(1),N7(2)]] is altered as could be shown diethylpyrocarbonate sensitivity of adenines just downstream of the lesion. However the adenines just downstream of another cisplatin adduct, cis-[Pt(NH3)2[d(GpCpG)-N7(1),N7(3)]], did not become diethylpyrocarbonate sensitive in the preincision complex although this complex is incision proficient.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protein-DNA interactions and alterations in the DNA structure upon UvrB-DNA preincision complex formation during nucleotide excision repair in Escherichia coli. 806 Sep 95

The UvrABC endonuclease from Escherichia coli repairs a broad spectrum of DNA lesions with variable efficiencies. The effectiveness of repair is influenced by the nature of the lesion, the local DNA sequence, and/or the topology of the DNA. To get a better understanding of the aspects of this multistep repair reaction that determine the effectiveness of repair, we compared the incision efficiencies of linear DNA fragments containing either a site-specific cis-[Pt(NH3)2(d(GpG)-N7(1),-N7(2)]] or a cis- Pt(NH3)2[d(GpCpG)-N7(1),-N7(3)]] adduct. Overall the DNA with the cis-PtGG adduct was incised about 3.5 times more efficiently than the cis-Pt.GCG-containing DNA. The rate of UvrB-DNA preincision complex formation for both lesions was similar and high in relation to the incision. DNase I footprints, however, showed that the local structure of the two preincision complexes is different. An assay was developed to measure the binding of UvrC to the preincision complexes and it was found that the binding rate of UvrC to the more slowly incised cis-Pt.GCG preincision complex was higher than to the cis-Pt.GG preincision complex. This most likely reflects a qualitative difference in preincision complex structures. For both lesions the binding of UvrC to the preincision complex was fast compared to the kinetics of actual incision. Apparently, direct incision of cisplatin damage requires an additional conformational change after the binding of UvrC.
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PMID:The actual incision determines the efficiency of repair of cisplatin-damaged DNA by the Escherichia coli UvrABC endonuclease. 811 Jul 82

A method is described for the incorporation of 2'-deoxy-2-thiouridine (dS2U) and 2'-deoxy-2-thiothymidine (dS2T) into oligodeoxynucleotides at predetermined positions. This requires N3 or O4-acylation of dS2U and dS2T with toluoyl chloride. These base-protected thiopyrimidines are completely stable toward the aqueous iodine oxidation reagent used in the phosphoramidite DNA synthesis method. The toluoyl protecting group is removed during the standard post-synthetic ammonia treatment. This novel protection strategy allows dS2U and dS2T to be efficiently incorporated into oligodeoxynucleotides at predetermined sites without the usual problem of desulfurization and decomposition. Several 14-mers containing the Eco-RI recognition site (dGGCGGAAXXCCGCC and dGGCGGAAXXCGCGG, where X represents dT, dS2U or dS2T) have been synthesized and characterized by base composition, thermal denaturation, CD spectroscopy and endonuclease substrate activity.
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PMID:Synthesis of oligodeoxynucleotides containing 2-thiopyrimidine residues--a new protection scheme. 819 Jun 35

Using CD spectroscopic and kinetic analysis, a refined mechanism of Co(NH3)6(3+) action on activity of Serratia marcescens nuclease was elucidated. The mechanism was identical with previously found mechanisms of Mg2+ and C7H5O2Hg+. Similarly to Mg2+ and C7H5O2Hg+, Co(NH3)6(3+) binding to the DNA substrate induced changes in the secondary structure which resulted in changes of the enzymatic activity of the S. marcescens nuclease. Upon binding of 0.03 Co(NH3)6(3+) per DNA phosphate, highly polymerized DNA displayed A-form characteristics. The DNA transition from B-form to A-form intermediate was followed by a decrease of the nuclease activity. The diminishing nuclease activity was consistent with diminishing values of Km and Kcat. Co(NH3)6(3+) binding to the highly polymerized DNA caused a 1.7-2.8-fold decrease in Km, and 13.3-19.9 decrease in Vmax compared with Mg-DNA complex. A vast excess of Co(NH3)6(3+) did not affect the activity of S. marcescens nuclease if the DNA in the assay mixture remained in its B-form conformation. Preincubation of S. marcescens nuclease with Co(NH3)6(3+) did not influence the tertiary structure of the enzyme.
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PMID:Action of hexaamminecobalt on the activity of Serratia marcescens nuclease. 1268 Jul 8


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