期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：3
页码：1199-1203
DOI：10.1073/pnas.75.3.1199
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：An approach to the study of protein receptor sites in protein mixtures or supramolecular assemblies by using fluorescence spectroscopy is described. This approach, fluorescent photoaffinity labeling, combines the merits of photoaffinity labeling to attain site-directed reactivity with the probing power of fluorescent ligands. A fluorescent photoaffinity label for cyclic AMP receptor sites of cyclic AMP-dependent protein kinases was synthesized in both unlabeled and radioactive forms. The probe, 8-azido-1,N6-ethenoadenosine 3',5'-cyclic monophosphate, mimics cyclic AMP in its ability to stimulate the phosphotransferase activity of the protein kinases and strongly competes with cyclic AMP for its binding sites in all preparations so far tested. Photolysis, after equilibration of protein kinase and 8-azido-1,N6-ethenoadenosine 3',5'-cyclic monophosphate in the dark, effects binding of the intermediate nitrene irreversibly and specifically to the cyclic AMP sites with the development of fluorescence. Excess reagent and low molecular weight photolytic products are removable by dialysis. Studies of a crude beef heart preparation containing cyclic AMP-dependent protein kinase suggest that the cyclic AMP binding sites are hydrophobic in nature and strongly immobilize the adenine moiety of the cyclic nucleotide.
