Metal Ion Activation of Phosphate Transfer by Bidentate Coordination

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Science  18 Apr 1969:
Vol. 164, Issue 3877, pp. 320-321
DOI: 10.1126/science.164.3877.320


The hydrolysis of methyl phosphate bound to the triethylenetetramine-cobalt(III) ion is much faster than the hydrolysis of either dimethyl phosphate bound to the same cation or methyl phosphate bound to the pentamminecobalt-(III) ion. The rate enhancement is attributed to bidenate coordination of the methyl phosphate. This feature suggests a pseudorotation mechanism analogous to that proposed by Westheimer for the hydrolysis of ethylene methyl phosphate. Stabilization of bidentate coordination might play a role in metal ion activation of phosphate-transfer enzymes.

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