Pyrophosphorolysis and enzymic synthesis of cytidine diphosphate glycerol and cytidine diphosphate ribitol

Abstract

An enzyme in the soluble fraction of extracts of Lacto-bacillus arabinosus [plantarum] 17-5 synthesized cytidine diphosphate glycerol from cytidine triphosphate and L-[alpha]-glycerol phosphate. The enzyme also formed cytidine triphosphate together with L-[alpha]-glycerol phosphate from cytidine diphosphate glycerol and pyrophosphate. Stoicheiometric measurements showed that the reactions take place according to the equation Cytidine triphosphate + L-[alpha]-glycerol phosphate cytidine diphosphate glycerol + pyrophosphate. It is proposed to name the enzyme cytidine diphosphate glycerol pyrophosphorylase. Fractionation of L. arabinosus extracts purified cytidine diphosphate glycerol pyrophosphorylase 24-fold. It was necessary to add Mg++, Co++ or Mn++ ions to promote enzyme activity. The optimum pH was 7 in tris-maleate buffer and pH 8 in tris-hydrochloric acid buffer. Purified preparations of cytidine diphosphate glycerol pyrophosphorylase were not active towards cytidine diphosphate ribitol. ATP, inosine triphosphate or uridine triphosphate did not replace cytidine triphos-phate, and ribitol phosphate, phosphocholine or phosphoethanolamine did not replace glycerol phosphate as substrates for the enzyme. An enzyme in the soluble fraction of extracts of Staphylococcus aureus H synthesized cytidine diphosphate ribitol from cytidine triphosphate and D-ribitol 5-phosphate, and formed cytidine triphosphate from cytidine diphosphate ribitol and pyrophosphate. Stoicheiometric measurements indicated that the reactions take place according to the equation: Cytidine triphosphate + D-ribitol 5-phosphate[long dash]- cytidine diphosphate ribitol + pyrophosphate. It is proposed to call the enzyme cytidine diphosphate ribitol pyrophosphorylase. Cytidine diphosphate ribitol pyrophosphorylase is present in extracts of L. arabinosus but absent from purified preparations of cytidine diphosphate glycerol pyrophosphorylase. Both cytidine diphosphate glycerol- and cytidine diphosphate ribitol-pyrophosphorylase activities were detected in extracts of Bacillus subtilis, Propionibacterium shermanii, Chlorella vulgaris and baker''s yeast as well as L. arabinosus and S. aureus. Cytidine diphosphate glycerol-pyrophosphorylase activity was detected in extracts from Escherichia coli and cytidine diphosphate ribitol-pyrophosphorylase activity in Streptococcus lactis R.