S-Adenosylmethionine serves as a methyl group donor in numerous transmethylation reactions and plays a role in the biosynthesis of polyamines and ethylene. We have cloned and sequenced an S-adenosylmethionine synthetase gene (sam-1) of Arabidopsis thaliana. The deduced polypeptide sequence of the enzyme has extensive homology with the corresponding enzymes of Escherichia coli and yeast. Genomic...

ing a H-atom from substrate. These and other kinetics studies demonstrated that PFL-AE could undergo multiple turnover events, with the 150 PFL activations per PFL-AE reported in Table 1 not the upper limit, but rather a number limited by the PFL:PFL-AE ratio in the steady-state kinetics assays. As can be seen from the data summarized in Table 1, PFL-AE is one of the few radical SAM enzymes dem...

Two experiments were conducted with weanling Sprague-Dawley rats to determine whether changes in S-adenosylmethionine utilization or metabolism contribute to the diverse responses to boron deprivation. In both experiments, four treatment groups of 15 male rats were fed ground corn-casein based diets that contained an average of 0.05 mg (experiment 1) or 0.15 mg (experiment 2) boron/kg. In exper...

Folate catabolism involves cleavage of the C(9)-N(10) bond to form p-aminobenzoylgluamate (PABG) and pterin. PABG is then acetylated by human arylamine N-acetyltransferase 1 (NAT1) before excretion in the urine. Mice null for the murine NAT1 homolog (Nat2) show several phenotypes consistent with altered folate homeostasis. However, the exact role of Nat2 in the folate pathway in vivo has not be...

The effects on cultured baby hamster kidney cells of 1-aminooxy-3-aminopropane, a potent new inhibitor of mammalian ornithine and S-adenosylmethionine decarboxylases and of spermidine synthase, were studied. At 0.5 mM concentration in the culture medium, the drug did not interfere with the transmethylation-transsulfuration pathway nor with the polyamine transport system, but it blocked the prol...

Inactivation of rat S-adenosylmethionine decarboxylase by l,l’-[(methylethanediylidene)dinitrilolbis(3-aminoguanidine) was studied both in vitro and in vivo. When incubated with the purified rat liver enzyme in the presence of putrestine this compound was a potent irreversible inhibitor. Inactivation proceeded as a first order reaction, which varied with the concentration of drug added but show...

Inactivation of rat S-adenosylmethionine decarboxylase by l,l’-[(methylethanediylidene)dinitrilolbis(3-aminoguanidine) was studied both in vitro and in vivo. When incubated with the purified rat liver enzyme in the presence of putrestine this compound was a potent irreversible inhibitor. Inactivation proceeded as a first order reaction, which varied with the concentration of drug added but show...