| Coenzyme A thioesters have attracted considerable attention since they represent an important class of activated intermediates in various biological pathways. It is estimated that approximately 4% of all known enzymes require CoA or CoA thioesters as substrates. The present investigation describes the optimization of the synthesis of surrogate coenzyme A thioesters that will be used to dissect the proposed mechanism of an acyltransferase. Modifications of the previously described method by Walker et al. (Walker, K., Fujisaki, S., Long, R. & Croteau, R. Proc. Natl. Acad. Sci., U.S.A. 2002, 99, 12715) resulted in improvement of yields from submiligram quantity (∼30%) to near quantitative conversion (65-70%) with identical reaction conditions; this was most apparent upon re-synthesis of two productive 3-amino-3-phenylpropanoid CoAs synthesized in the previous study. Modification of an existing method for the coupling of the 3'-amino-3'-phenylpropanoid sidechain of TaxolRTM onto C13 of baccatin III is described that will give access to a library of TaxolRTM derivatives including second-generation taxanes in a short synthetic route. Furthermore, synthesis of radiolabeled baccatin III, an advanced taxol biosynthetic pathway intermediate, is also described. |
