Glucosides, biosynthesis

Figure 3.8 Metabolic cross-talk between glucosinolate and cyanogenic glucoside biosynthesis in transgenic Arabidopsis plants (according to Kristensen et a ., 2005).

The amount of these unknown cyanogens could be significantly enhanced by applying osmotic stress to the cultures. In addition, l-(4 -hydroxvphenyl)-2-nitroethane was present in the cultures. This compound is thought to be a side-product of cyanogenic glucoside biosynthesis (see Section 3.2.4). 

KOCH, B.M., SIBBESEN, O., HALKIER, B.A., SVENDSEN, I., M0LLER, B.L., The primary sequence of cytochrome P450tyr, the multifunctional N-hydroxylase catalyzing the conversion of L-tyrosine to /7-hydroxyphenylacetaldehyde oxime in the biosynthesis of the cyanogenic glucoside dhurrin in Sorghum bicolor (L.) Moench, Arch. Biochem. Biophys., 1995,323, 177-186. 

CYP79s in the Biosynthesis of Cyanogenic Glucosides and Glucosinolates 233 The Oxime-Metabolizing Enzyme as Branch Point between the Cyanogenic... 

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. 

Dutton, G.J. and tiling, H.P.A. (1972) Mechanism of biosynthesis of thio-p-D-glucuronides and thio-p-D-glucosides. 

The riocus encodes the enzyme flavonoid 3 -hydroxylase (F3 H) [17, 18], and is an important controller of flux in the anthocyanin pathway in soybean seed coats (Fig. 4.1). F3 H diverts metabolic flux away from biosynthesis of orange (pelargoni-din) and blue (delphinidin) anthocyanins toward the red cyanidin-3-(9-glucoside, which is the main anthocyanin in the seed coats of black soybean [7, 8]. T increases the accumulation of delphidin-3-O-glucoside in black seed coats, even though it is not required for its biosynthesis [19]. Possible mechanisms for this include positive feedback, or the stabilization of the putative anthocyanin biosynthetic metabolon [20] by F3 Fl-derived membrane anchoring (Fig. 4.1). 

Orr JD, Lynn DG (1992) Biosynthesis of dehydrodiconiferyl alcohol glucosides implications for the control of tobacco ceU growth. Plant Physiol 98 343-352... 

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