J. Biol. Chem., Vol. 255, Issue 14, 6675-6678, 07, 1980
Decarboxylated S-adenosylmethionine in mammalian cells
H Hibasami, JL Hoffman and AE Pegg
The content of decarboxylated S-adenosylmethionine in rat tissues was found
to be of the order of 0.9 to 2.5 nmol/g wet weight, about 2 to 4% of the
content of S-adenosylmethionine. Three methods were used for
determinations: separation by high pressure liquid chromatography followed
by quantitation using UV absorbance, separation by paper electrophoresis
after labeling with radioactive methionine to get the ratio of
S-adenosylmethionine to decarboxylated S-adenosylmethionine, and separation
by electrophoresis followed by elution and assay by an isotope dilution
technique using spermidine synthase. The three methods gave comparable
results, although the labeling with methionine appeared to slightly
overestimate levels in the liver. Hepatic decarboxylated S-
adenosylmethionine content was reduced by more than 90% for at least 8 h by
treatment with methylglyoxal bis(guanylhydrazone), a potent reversible
inhibitor of S-adenosylmethionine decarboxylase, but had returned to
control levels by 24 h. The related irreversible inhibitor,
1,1'-[(methylethanediylidene)-dinitrilo]bis(3-aminoguanidine), reduced
levels slightly less to about 20% of control, but maintained them at this
value for 2 days.
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