Biosynthesis of trans,trans- and cis,trans-farnesols by soluble enzymes from tissue cultures of Andrographis paniculata |
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| Authors: | Karl H Overton and Frank M Roberts |
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| Institution: | Plant Tissue Culture Unit, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K. |
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| Abstract: | A cell-free system obtained from tissue cultures of Andrographis paniculata produces 2-trans,6-trans-farnesol (trans,trans-farnesol) and 2-cis,6-trans-farnesol (cis,trans-farnesol) (5:1), incorporating 10% of the radioactivity from 3R-2-(14)C]mevalonate. There is total loss of (3)H from 3RS-2-(14)C,(4S)-4-(3)H(1)]mevalonate and total retention from the (4R) isomer in both the trans,trans-farnesol and cis,trans-farnesol formed. When 3RS-2-(14)C,5-(3)H(2)]mevalonate is used as substrate, there is total retention of (3)H in the trans,trans-farnesol, but loss of one-sixth of the (3)H in the cis,trans-farnesol. With (1R)- and (1S)-4,8,12-(14)C(3),1-(3)H(1)]-trans,trans -farnesol and (1R)- and (1S)-4,8,12-(14)C(3),1-(3)H(1)]-cis, trans-farnesol as substrates, the label is lost from the (1R)-cis,trans and (1S)-trans,trans isomers but retained in the (1R)-trans,trans and (1S)-cis,trans isomers; this shows that the pro-1S hydrogen is exchanged in the conversion of trans,trans-farnesol into cis,trans-farnesol and the pro-1R hydrogen in the conversion of cis,trans-farnesol into trans,trans-farnesol. (1R)-1-(3)H(1)]-trans,trans-Farnesol and (1R)-1-(3)H(1)]-cis,trans-farnesol have been synthesized by asymmetric chemical synthesis and exchanged with liver alcohol dehydrogenase. Both the trans- and the cis-alcohol exchange the pro-1R hydrogen atom. |
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