In vitro biosynthesis of the cyanogenic glucoside taxiphyllin in Triglochin maritima

When l-tyrosine and NADPH were incubated with a microsomal fraction from Triglochin maritima seedlings, 4-hydroxymandelonitrile (measured as 4-hydroxybenzaldehyde and HCN) and 4-hydroxyphenylacetonitrile were synthesized. Taxiphyllin, a cyanogenic glucoside occurring in this plant, was formed when UDPglucose and a soluble protein fraction from T. maritima, were also included in the assay. The above glucosyl transferase activity also produced taxiphyllin when incubated with R,S-4-hydroxymandelonitrile and UDPglucose. No trace of dhurrin, the enantiomer of taxiphyllin, was detected. The highest microsomal activity was found in 5- to 6-day-old etiolated seedlings. It was absolutely necessary to remove all seed coats from the seedlings in order to obtain an active microsomal fraction.