Acyl adenosyl phosphate, from

Acyl adenosyl phosphate, from carboxylic acids, 800-801 mechanism of formation of. 800-801... 

An acyl phosphate is formed by nucleophilic attack of a carboxylate ion on the y-phosphorus (the phosphorus farthest away from the adenosyl group) of ATP. Attack of the nucleophile breaks the phosphoanhydride bond (rather than the tt bond), so an intermediate is not formed. Essentially, it is an Sn2 reaction with an adenosine diphosphate leaving group. 

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