Open AccessA Study of Some Molecular and Kinetic Properties of Two tRNA Methyltransferases from Mouse Plasmocytoma
Author(s) -
NAU François,
PHAMCœURJOLY Ghislaine,
DUBERT JeanMarie
Publication year - 1983
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1983.tb07145.x
Subject(s) - transfer rna , methyltransferase , enzyme , centrifugation , chemistry , substrate (aquarium) , biochemistry , magnesium , cytosine , ionic strength , size exclusion chromatography , differential centrifugation , microbiology and biotechnology , biology , rna , methylation , dna , organic chemistry , ecology , gene , aqueous solution
A tRNA(adenine‐1)methyltransferase and a tRNA(cytosine‐5)methyltransferase have been partially purified from mouse plasmocytoma MOPC 173. Their apparent M r are 2—230000 and 110000—140000, respectively, as determined by gel filtration and density gradient centrifugation. Both enzymes exhibit maximum activity in the presence of high concentrations of monovalent cations (0.175 M and 0.25 M KCl, respectively) and in the absence of magnesium. Their kinetic constants have been determined at various KCl concentrations, with several tRNA species as substrates. These constants may differ by more than one order of magnitude, depending upon the substrate used, and they are strongly dependent upon the ionic concentration as well. The possibility that the tRNA(adenine‐1)methyltransferase from mouse plasmocytoma is different from the homolgous enzyme purified from a normal rat tissue [Glick, J. M. and Leboy, P. S. (1977) J. Biol. Chem. 252 , 4790–4795] is discussed.