Evidence that xylosyladenine affects methylation by inhibition of S-adenosyl-L-methionine synthesis.

The adenosine analogs, 9-beta-D-xylofuranosyladenine (XA) and 3'-deoxyadenosine (cordycepin) were tested for their ability to interfer with S-adenosyl-L-methionine (SAM) formation in L1210 cells in vitro. XA inhibited the incorporation of [3H]methionine into SAM in a mixed-competitive manner, while cordycepin was not inhibitory. The adenosine deaminase inhibitor, 2-deoxy-coformycin produced a marked potentiation of the inhibitory effect of XA on Sam synthesis, but did not affect the inactivity of cordycepin.

Measurement of S-adenosyl-L-methionine levels by SP Sephadex chromatography.

Cation-exchange chromatography with sulfopropyl Sephadex was used to measure the levels of S-[methyl-3H]adenosyl-L-methionine synthesized by L1210 cells in vitro. Separation of S-[methyl-3H]adenosyl-L-methionine from [methyl-3H]methionine and other metabolites was achieved by stepwise elution with varying concentrations of HCl.