Arsenic mononucleotides. Separation by high-performance liquid chromatography and identification with myokinase and adenylate deaminase

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Abstract
The spontaneous formation of arsenic mononucleotides was detected in mixtures of arsenate and inosine or adenosine or its deoxy analogs. These compounds were separated by high-performance liquid chromatography and identified by their behavior in the presence of myokinase and adenylate deaminase. The nucleoside 5''-arsenates are formed preferentially to the 2''- and 3''-arsenate analogs. All arsenic nucleotides detected showed similar kinetic and equilibrium constants of formation: about 8 .times. 10-4 M-1 s-1 and 2 .times. 10-3 M-1, respectively. These values are several orders of magnitude greater than those of their phosphoric analogs. The adenosine 5''-arsenate was able to substitute for 5''-AMP in the reaction of myokinase and adenylate deaminase. The substitutions of the 2''- or 3''-H for hydroxyl groups in the ribose moiety of this compound slightly affected its suitability as substrate for myokinase but had drastic effect in the case of adenylate deaminase. The half-life of the arsenic nucleotides, at pH 7.0 and 25.degree. C, ranged from 30-45 min. The lability of these compounds is increased during catalysis with myokinase. Results on the reaction mechanisms of myokinase with adenosine 5''-arsenate indicate that the mixed-anhydride analog to ADP, adenosine 5''-(arsenate phosphate), is not detected either because it is not formed in the reaction with this enzyme or because it is rapidly hydrolyzed.

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