tracer experiments with l-methionine-u- ( 14 ) c , l-methionine-methyl- ( 3 ) h , and l-homocysteine thiolactone- ( 35 ) s indicated that smm was capable of acting as a methyl donor , and that in senescent segments the methyl group was utilized for methionine production with homocysteine serving as methyl acceptor .
C0042889
smm
C0025646
methionine