The effect of arsenate on bacterial citrulline breakdown

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Abstract
The rate of conversion of citrulline into ornithine, CO2 and ammonia by a cell-free extract of Streptococcus faecalis in the presence of phosphate and adenosine diphosphate (ADP) is increased by addition of arsenate. In the presence of arsenate, citrulline is decomposed by the extract without addition of phosphate and ADP. The max. rate in the presence of arsenate is about 5 times higher than that in the presence of ADP and phosphate. The products formed from citrulline are the same with arsenate as with ADP and phosphate, the overall reaction in the presence of arsenate being; citrulline + H2O = ornithine + CO2 + NH3. The effect of arsenate is reduced by addition of phosphate, fluoride, or iodoacetate. Inhibition by phosphate is competitive. The mechanism of the action of arsenate is discussed. An improved method for estimation of citrulline is descr., it is based on the diacetyl reaction of Fearon (Biochem. Jour., 33, p. 902,1939).