[32P]2N3ATP and [32P]8N3ATP can provide a wealth of information regarding ATP binding proteins. With these two structural photoaffinity isomers of ATP, it is possible to completely map out the adenine base binding portion of the active site of virtually any ATP binding protein. The active site site peptides of a protein can be easily determined using a combination of photoaffinity labeling, proteolytic digestion, immobilized metal affinity chromatography (IMAC) followed by reverse phase HPLC. These two photoaffinity analogs can be used to detect changes in specific ATP binding proteins in disease states such as Alzheimer's disease. The nonhydrolyzable ATP photoaffinity analogs, [32P]ATP-azidoanilide and [32P]ATP-benzophenone, can be used to study ATP binding proteins which posses a high rate of hydrolysis of the gamma phosphate. They can also be utilized to determine the phosphate binding domain peptides of proteins. Since the photoactive moieties of these two photoaffinity analogs are attached through the gamma phosphate and not the purine ring, they will sometimes afford greater binding efficiency to specific ATP bindings proteins which are adversely effected by base modification. For more information see ATP-azidoanilide.
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