Severin E S, Tkachuk V A, Guliaev N N
Biokhimiia. 1976 Feb;41(2):384-8.
Interaction of adenosine-3',5'-cyclosulphate (cAMS) cAMP analogue, having sulphur atom instead of phosphorus in a six-term cyclic system with pig brain proteinkinase and rabbit skeletal muscle phosphodiesterase is studied. The affinity of proteinkinase to cAMS was found to be in 25000 times lower than the affinity of cAMP, the affinity of cAMS to the active site of phosphodiesterase being high enough. It is suggested that in the regulatory subunit of proteinkinase positive kationic group participates in nucleotide binding by interacting with negative oxygen atom of six-term cyclophosphate system. There is no such a group in the active site of phospodiesterase, because the absence of negative charge in case of cAMS only slightly affects the constant of cAMS binding by phosphodiesterase.
研究了腺苷 - 3',5'-环硫酸酯（cAMS），一种在六元环系统中用硫原子取代磷原子的cAMP类似物，与猪脑蛋白激酶和兔骨骼肌磷酸二酯酶的相互作用。发现蛋白激酶对cAMS的亲和力比cAMP的亲和力低25000倍，而cAMS对磷酸二酯酶活性位点的亲和力足够高。有人提出，在蛋白激酶的调节亚基中，正阳离子基团通过与六元环磷酸系统的负氧原子相互作用参与核苷酸结合。在磷酸二酯酶的活性位点没有这样的基团，因为在cAMS的情况下没有负电荷只会轻微影响磷酸二酯酶结合cAMS的常数。
