Linamarin, biosynthesis

ANDERSEN, M.D., M0LLER, B.L., Cytochromes P450 from Cassava (Manihot esculenta Crantz) catalyzing the first steps in the biosynthesis of the cyanogenic glucosides linamarin and lotaustralin cloning, functional expression in Pichia pastoris and substrate specificity of the isolated recombinant enzymes, J. Biol. Chem., 2000,275, 1966-1975. 

Antinutrient Cassava [18] Suppression of enzymes (CYP79D1 and CYP79D2) involved with the biosynthesis of cyanogenic glucosides (decrease in linamarin)... 

Fig. 16.5. Biosynthesis of linamarin and lotaustralin (Koch et al., 1992 modified and used with permission of the copyright owner. Academic Press, Orlando, FL).

Forslund K, Morant M, Jorgensen B, Olsen CE, Asamizu E, Sato S, Tabata S, Bak S (2004) Biosynthesis of the nitrile glucosides rhodiocyanoside A and D and the cyanogenic glucosides lotaustralin and linamarin in Lotus iaponicas. Plant Physiol 135 71-84... 

Biosynthesis of linamarin and lotaustralin has been studied by Conn et al. (19, 149). On the basis of highly effective incorporation of " C-labelled L-valine into linamarin and of L-isoleucine into lotaustralin, they concluded that these amino acids are precursors of the two cyanoglucosides. Since the glucosyl transferase (UDP-glucose ketone cyanohydrin-yff-D-glucosyltransferase) was shown to be unable to distinguish between the two possible enantiomers - (i ,S)-2-hydroxy-2-methyl-butyro-nitriles - L-isoleucine ([3S]-Ls-isoleucine), which supplies the / -enantiomer, must be the sole precursor for naturally occurring (/ )-lotaustralin (149). It is quite possible that L-leucine is the precursor of acacipetalin, proacacipetalin, epiproacacipetalin, and cardiospermin. 

Butler G W, Conn E E 1964 Biosynthesis of the cyanogenic glucosides, linamarin and lotaustralin. I. Labeling studies in vivo with Linum usitatissimum. J Biol Chem 239 1674-1679... 

Narty F 1968 Studies on cassava, Manihot utilissima Pohl I. Cyanogenesis The biosynthesis of linamarin and lotaustralin in etiolated seedlings. Phytochemistry 7 1307-1312... 

Analogous results were obtained in a study of the biosynthesis of linamarin (147) in flax and from this plant an enzyme has been isolated which specifically catalyses the last step of glucose transfer ° in the biosynthetic pathway. 

Figure 10.9 The biosynthesis of the cyanogenic glycosides linamarin and lotaustralin from amino-acids in the burnet moth. The dot on nitrogen and the prime and double prime on carbon represent N and respectively. Labelling showed that these atoms were retained in place during the synthesis...

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