48 マロプレノールの生合成 : Z-イソプレン残基の生成におけるメバロン酸のpro-4S水素原子の異常脱離

概要

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The malloprenols isolated from the leaves of Mallotus japonicus were elucidated to be (2z,6z,10z,14z,18z,22z,26E,30E,34E)-3,7,11,15, 19,23,27,31,35,39-decamethyl-2,6,10,14,18,22,26,30,34,38-tetraconta-decaen-1-ol and its C_<45>- and C_<55>-homologues, on the basis of observations of mass peaks due to succesive loss of an isoprene residue and ^1H NMR signal due to allylic methyls, methylenes, cis-and trans-olefinic protons, and an allylic primary hydroxyl group and demonstrations of the arrangement of the E- and z-isoprene units by comparing the incorporation of a homolog of all E-prenyl-1-^3H_2 pyrophosphates with that of the corresponding 2-z isomers. In the biosynthesis of isoprenoids, it is a tenet that the pro-4S hydrogen atom of mevalonic acid (MVA) is lost in the formation of an E-isoprene residue, while the pro-4R hydrogen atom is eliminated in the formation of a z-isoprene residue. However, the unusual elimination of the pro-4s hydrogen atom of mevalonic acid in the biological formation of z-isoprene residues of malloprenols by Mallotus japonicus was observed in feeding experiments of mevalonic acid-2-^<14>C,(4R)-4-^3H and its (4S)-4-^3H isomer. This is in contrast to the doctrinal isoprenoid pathway that the pro-4R hydrogen atom is eliminated in the formation of a z-isoprene residue.
天然有機化合物討論会の論文
1980-09-10