期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：1
页码：170-174
DOI：10.1073/pnas.76.1.170
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：L-[U-14C]Methionine fed to apple tissue was efficiently converted to ethylene when the tissue was incubated in air. In nitrogen, however, it was not metabolized to ethylene but was instead converted to 1-aminocyclopropane-1-carboxylic acid (ACC). When apple tissues were fed with L-[methyl-14C]methionine or L-[35S]methionine and incubated in nitrogen, radioactivity was found subsequently in methylthioribose. This suggests that methionine is first converted to S-adenosylmethionine which is in turn fragmented to ACC and methylthioadenosine. Methylthioadenosine is then hydrolyzed to methylthioribose. The conclusion that ACC is an intermediate in the conversion of methionine to ethylene is based on the following observations: Labeled ACC was efficiently converted to ethylene by apple tissue incubated in air; the conversion of labeled methionine to ethylene was greatly decreased in the presence of unlabeled ACC, but the conversion of labeled ACC to ethylene was little affected by the presence of unlabeled methionine; and 2-amino-4-(2'-aminoethoxy)trans-3-butenoic acid, a potent inhibitor of pyridoxal phosphate-mediated enzyme reactions, greatly inhibited the conversion of methionine to ethylene but did not inhibit conversion of ACC to ethylene. These data indicate the following sequence for the pathway of ethylene biosynthesis in apple tissue: methionine [->] S-adenosylmethionine [->] ACC [->] ethylene. A possible mechanism accounting for these reactions is presented.
关键词：S -adenosylmethionine ; aminoethoxyvinylglycine ; fruit ripening ; apple
