Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.5.1.2 (DNA ligase)
 2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NB8 DNA ligase from an extract of Thermus thermophilus HB8 could catalyze blunt-end ligation in the presence of high concentration of polyethylene glycols (PEG) or in the presence of polyamines. In the presence of high molecular weight PEG 20,000, 6,000, or 1,000 (8-28%), the enzyme catalyzed blunt-end intermolecular joining to yield linear oligomers, but no circular DNA forms. But in the presence of low molecular PEG 400, 200 (8-80%), or the monomer, ethylene glycol (16-80%), the circular forms were also detected by intramolecular ligation. In the presence of polyamines, the blunt-end ligation products were linear oligomers and the optimum concentrations were as follows: caldopentamine (0.05 mM), thermine (0.1-0.2 mM), spermine (0.2 mM), thermospermine (0.4 mM), and sperminediol (0.75 mM). Spermidine and putrescine were less capable of producing oligomers. PEG and polyamines elevated the ligation temperature by HB8 DNA ligase. The optimum temperature of blunt-end ligation was about 65 degrees C.
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PMID:Thermophilic HB8 DNA ligase: effects of polyethylene glycols and polyamines on blunt-end ligation of DNA. 375 25

Single-strand gaps in DNA molecules were found to be a substrate for T4 DNA ligase. Sealing of the gaps was optimal at the same conditions as ligation of blunt-ended DNA molecules. Spermidine at a concentration of 2 mM stimulated the ligation of gaps, as well as the joining of DNA molecules with cohesive and blunt ends. In addition, spermidine reduced the optimal ATP concentration. The ligation of single-stranded gaps was a slow process, reaching a plateau after several hours at 25 degrees C. Approximately 10% of circular duplex plasmid pBR322 DNA molecules with a gap of 1-5 nucleotides could be converted to a covalently closed form. When such molecules were used for transformation of E. coli cells deletion mutants were obtained at a high frequency. The size and position of the gaps and the deletions were equivalent, confirming that T4 DNA ligase was sealing the gaps.
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PMID:Sealing of gaps in duplex DNA by T4 DNA ligase. 704 Oct 91