Partial purification and characterization of a ribonucleic acid N2-guanine methyltransferase associated with avian myeloblastosis virus.
Biochemistry, 1979/11/13;18(23):5253-8.
PMID: 227452
Impact factor: 3.321
Abstract
A nucleic acid methylase, N2-guanine ribonucleic acid (RNA) methyltransferase, which is associated with type C RNA tumor viruses, has been purified from avian myeloblastosis virions by gel filtration on Sephadex G-200, followed by chromatography on hydroxylapatite. The molecular weight estimated by gel filtration is 220 000, and the methylase activity has a pH optimum of 7.6--7.9. Magnesium and ammonium ions both stimulate activity 1.5-fold at 9.5 mM and 0.36 M, respectively, but apparently neither is essential for activity. Both daunomycin and adriamycin, antineoplastic drugs, also increase activity 1.5-fold at 1 mM. The enzyme was purified 120-fold from the virions and the activity is partially stabilized by dithiothretiol, but large losses were sustained during 24-h dialysis. The purified enzyme retains 75% of its activity on storage at -25 degrees C for 2 months in buffer containing 50% glycerol. Escherichia coli tRNAPhe and tRNAVal are preferred substrates with methylation occurring at position 10 of E. coli tRNAPhe.
MeSH terms
Avian Leukosis Virus; Avian Myeloblastosis Virus; Daunorubicin; Doxorubicin; Enzyme Activation; Guanine; Kinetics; Magnesium; Molecular Weight; Substrate Specificity; tRNA Methyltransferases
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