34 ^<13>C-D Couplingを利用した生合成研究 : 〔S-^<13>CD_3〕-L-MethionineによるO-メチル化とC-メチル化

抄録

The origin and fate of protons play an important role in understanding the detailed mechanism of natural products biosynthsis. Here to fore a biosynthetic studies with carbon-13 have only been concerned with the origin of carbon skeletons. We report the use of ^<13>C-D coupling as a new method for the detection of the fate of protons during the biosynthesis of natural products. [S-^<13>CD_3]-(90% ^<13>C, 99.8% D_3)-L-Methionine was fed to the fermentation media of Pseudeurotium ovalis. Ovalicin (graphinone) and ergosterol were isolated from the broth and mycelia. In the case of ovalicin the O-methyl carbon appeared as a septet (1:3:6:7:6:3:1) with an isotope shift in the ^<13>Cnmr spectrum. On the other hand the C_<28>-methyl carbon of ergosterol appeared as a mixture of quintet (1:2:3:2:1) and triplet (1:1:1) signals. These results show that the mechanism of O-methylatian and C-methylation from the C_1 unit of methionine are different. The results of a ^<13>CH_3-^<13>CO_2Na (90% enriched) feeding experiment indicate that a bergamotene type intermediate is compatible in ovalicin biosynthesis.