Biosynthesis of apiose in vivo

The elucidation of the biosynthetic pathway of apiose was founded on extensive, isotope-incorporation experiments in L. minor,85,66-82,83 

gifofoa,65-79-83 and P. crispum.m,7 , H2 H4,H5 In general, the results of these in vivo investigations, as well as those of in vitro biosynthetic studies, support the hypothesis proposed for the synthesis of D-apiose polysaccharides and apiin (4) by Grisebach and Dobereiner82 (see Fig. 1). They postulated that decarboxylation of a nucleoside 

-Transglycosylation of D-Apiose from UDP-D-apiose (5). (Studies in vitro showed that UDP-D-apiose uridine 5 -[3-C-(hydroxymethyl)-a-D-erythrofiiranosyl pyrophosphate] functions in a transglycosylation reaction. The product is apiin, 4, 5-dihydroxyflavon-7-yl 2-0-[3-C-(hydroxymethyl)-/3-D-erythrofuranosyl]-/8-D-glucopyran-oside (4), formed through the aid of an acceptor molecule.7 Additional products that may be formed by transglycosylation from an apiose donor-molecule include, principally, apiose-containing polysaccharides.) 

When L-[l-14C]arabinose was supplied to L. gibba (duckweed), both the arabinosyl and xylosyl residues of the cell-wall polysac- 

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