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Abstract
SUMMARY: Choline, a component of the wall teichoic acid of Streptococcus pneumoniae, was converted to cytidine diphosphocholine via choline phosphate by enzymes which were identified in cell-free extracts of the pneumococcus. The first enzyme, choline kinase, was investigated in some detail. It appeared to have a pH optimum of 7·3 to 7·4 and was stimulated by Mg2+. Kinetic studies gave an apparent Michaelis constant (K m) for ATP of 1 mm, and for choline of 0·19 mm, with V max values of 3 nmol min−1 (mg protein)−1 and 0·5 nmol min−1 (mg protein)−1 respectively. The second enzyme, CDPcholine pyrophosphorylase was specific for CTP and had a requirement for Mg2+ with an optimum at 7 mm.
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© Society for General Microbiology, 1977