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)

A general method has been developed for the recovery of any DNA fragment inserted into a cloning vehicle containing a single endonuclease PstI site. Endonuclease PstI sites are regenerated by the addition of one or more deoxyguanosine residues to the 3' termini of the PstI-cleaved vehicle by terminal deoxynucleotidyl transferase. Chain elongation by terminal deoxynucleotidyl transferase is then continued with dITP, dATP or dGTP. A plasmid vehicle, pAO1, containing a single PstI site has been constructed. Insertional (foreign) DNA fragments that were "tailed" with dCTP have been annealed to PstI-cleaved pAO1 that was "tailed" with dGTP. When the annealed fragments were used to transform competent Escherichia coli cells, the single-stranded DNA gaps in the recombinant plasmids were repaired. Plasmids recovered from transformed bacteria could be cleaved by PstI into the insertional DNA with dG:dC tracts and linear pAO1 molecules.
 ...
PMID:Recovery of DNA fragments inserted by the "tailing" method: regeneration of PstI restriction sites. 626 21

A novel dNTP pyrophosphatase, Mj0226 from Methanococcus jannaschii, which catalyzes the hydrolysis of nucleoside triphosphates to the monophosphate and PPi, has been characterized. Mj0226 protein catalyzes hydrolysis of two major substrates, dITP and XTP, suggesting that the 6-keto group of hypoxanthine and xanthine is critical for interaction with the protein. Under optimal reaction conditions the k(ca)(t) /K(m) value for these substrates was approximately 10 000 times that with dATP. Neither endonuclease nor 3'-exonuclease activities were detected in this protein. Interestingly, dITP was efficiently inserted opposite a dC residue in a DNA template and four dNTPs were also incorporated opposite a hypoxanthine residue in template DNA by DNA polymerase I. Two protein homologs of Mj0226 from Escherichia coli and Archaeoglobus fulgidus were also cloned and purified. These have catalytic activities similar to Mj0226 protein under optimal conditions. The implications of these results have significance in understanding how homologous proteins, including Mj0226, act biologically in many organisms. It seems likely that Mj0226 and its homologs have a major role in preventing mutations caused by incorporation of dITP and XTP formed spontaneously in the nucleotide pool into DNA. This report is the first identification and functional characterization of an enzyme hydrolyzing non-canonical nucleotides, dITP and XTP.
 ...
PMID:Biochemical characterization of a novel hypoxanthine/xanthine dNTP pyrophosphatase from Methanococcus jannaschii. 1145 35