Mechanism-based inhibition of ribonucleoside diphosphate reductase from Corynebacterium nephridii by 2'-C-methyladenosine diphosphate.

The interaction of the adenosylcobalamin-dependent ribonucleoside diphosphate reductase of Corynebacterium nephridii with 2‘-C-methyladenosine diphosphate (2‘-C-methylADP) has been investigated in more detail [Ong, S. P., McFarlan, S. C., & Hogenkamp, H. P. C. (1993) Biochemistry 32, 11397−11404]. This nucleotide analog partitioned between normal reduction to 2‘-deoxy-2‘-C-methyladenosine diphosphate and decomposition to adenine, 2-methylene-3(2H)-4-methylfuranone, and presumably pyrophosphate. Reaction of the reduced enzyme with 2‘-C-methylADP caused the development of a chromophore at 318 nm that is characteristic of the modification of the enzyme by the furanone [Harris, G., Ator, M., & Stubbe, J. (1984) Biochemistry 23, 5214−5225]. Incubation of [5‘-3H2]-2‘-C-methylADP with reduced reductase resulted in the covalent incorporation of the radiolabel into the protein and into aquocobalamin. A similar incubation of the enzyme, the labeled nucleotide analog, and dithiothreitol resulted in the formation of ...