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

Behavior of the covalent [32P]- and [14C]AMP-RNA ligase complex under various conditions has been studied. The covalent structure is shown to be readily cleaved by acid and hydroxylamine and relatively stable to alkali and snake venom phosphodiesterase. Products of degradation of the AMP-RNA ligase and AMP-DNA ligase complexes were compared. The data obtained support the earlier assumption of a phosphoamide bond in the AMP-RNA ligase compound.
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PMID:[Hydrolytic stability of a covalent AMP-RNA ligase complex]. 299 84

Single strand specific mung bean nuclease was used to probe for regions of altered secondary structure in supercoiled PM2 DNA. Supercoiled DNA is cleaved greater than or equal to 10,000 times faster than the relaxed topoisomer. Catalytic quantities of enzyme convert supercoiled DNA to both nicked-circular and unit length linear forms at pH 5 but to predominantly the nicked-circular form near neutral pH. At the elevated enzyme concentrations required to cleave relaxed DNA, unit length linear DNA and smaller fragments are produced from pH 5 to 7. One nick per supercoiled DNA molecule is introduced at pH 6.6. The nicks are repairable by DNA ligase and are not strand-specific. Snake venom phosphodiesterase selectively cleaves the strand opposite the nicks, permitting restriction endonuclease mapping. The nicks occur at three specific sites. Sites at 0.75 and 0.76 map units are cleaved with equal frequency, while a site at 0.82 is cleaved less frequently. The former sites map near one of the eight known early denaturation regions of PM2 DNA, while the latter does not. Since most early denaturation sites are not cleaved, sites other than these dA + dT-rich regions may be the preferred locations of strand unwinding and separation in supercoiled PM2 DNA.
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PMID:Action of mung bean nuclease on supercoiled PM2 DNA. 628 55