Enzymic methods sugar phosphates

Figure 3 Conversion of ribose S-phosphate to sugar phosphate products by rat liver enzyme preparation (RLEP) (40). Details of the incubation, protein content and methods used are described in (42). For measurement of the max. catalytic capacity of RLEP see (43). Reprinted from International Journal of Biochemistry, 19. Williams John. F., Arora Krishan K. and Longnecker John P. The pentose pathway A random harvest, 69 Pages, 1987, with permission from Elsevier, http //www.sciencedirectcom/science/journal/l 3S7272S...

The most widely used and best developed enzyme-catalyzed phosphorylations are the ones that are coupled to ATP regeneration systems. Sugar phosphates, nucleoside phosphates and glycerides are the major classes of compounds prepared with these methods. 

A rapid, high yield synthesis of C-enriched intermediates of the pentose-phosphate pathway has been developed based on a combination of chemical and enzymic reactions. [l- C]Ribose and [l- C]arbinose 5-phospha,tes, available by the classical Kiliani method, were converted to a variety of specifically labelled 5-, 6-, 7-, and 8-carbon sugar phosphates (e.g.. D-erythro-pentulosc 5-phosphate, sedoheptulose mono- and di-phosphates) with the help of aldolase, transaldolase, and transketolase. ... 

The estimation of sugar phosphates with enzymes offers many possibilities. For instance, fructose 1,6-diphosphate can be estimated using aldolase, glucose 6-phosphate with the corresponding dehydrogenase, etc. Methods for the analysis of glucose i-phosphate, glucose 6-phosphate, fructose i-phos-phate and fructose 1,6-diphosphate have been described . 

D-Arabinose-5-phosphate isomerase, the first key enzyme in the synthesis of KDO, catalyzes the interconversion of D-ribulose-5-phosphate and D-arabinose-5-phosphate. This enzyme was briefly studied by Volk (18) and later by Lim and Cohen (19). Due to the instability of the enzyme, we have only purified this enzyme 100-fold. The reversible reaction is readily monitored by measuring the formation of the keto-sugar from the aldo-sugar by the method of Dische and Borenfreund (20). The K values for D-ribulose-5-phojsphate and D-arabinose-5-phosphate are 0.9 to 1.5 and 1 to 3 x 10 M, respectively. 

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