• 1 January 1977
    • journal article
    • research article
    • Vol. 252  (14) , 4790-4795
Abstract
An S-adenosylmethionine-dependent tRNA(adenine-1)-methyltransferase was purified 8000-fold from rat liver. This preparation gives a single band on polyacrylamide gel electrophoresis and is stable in long term storage. The enzyme has a MW of approximately 95,000. The single methylating capacity of this adenine-1-methyltransferase, using Escherichia coli .**GRAPHIC**. is methylation of the invariant adenine in the GT.PSI.C loop. The methylation reaction is dependent on added cation of 20-40 mM putrescine being most effective. The Km for S-adenosylmethionine was 0.3 .mu.M, while the Ki for the product inhibitor S-adenosylhomocysteine was 0.85 .mu.M. The Km for .**GRAPHIC**. is 12 nM, while that for .**GRAPHIC**. is 33 nM.