Design, Synthesis, and Chemical and Biological Properties of Cyclic ADP-4-Thioribose as a Stable Equivalent of Cyclic ADP-Ribose

Here we describe the successful synthesis of cyclic ADP-4-thioribose (cADPtR, ), designed as a stable mimic of cyclic ADP-ribose (cADPR, ), a Ca-mobilizing second messenger, in which the key N1-β-thioribosyladenosine structure was stereoselectively constructed by condensation between the imidazole nucleoside derivative and the 4-thioribosylamine via equilibrium in between the α-anomer () and the β-anomer () during the reaction course. cADPtR is, unlike cADPR, chemically and biologically stable, while it effectively mobilizes intracellular Ca like cADPR in various biological systems, such as sea urchin homogenate, NG108-15 neuronal cells, and Jurkat T-lymphocytes. Thus, cADPtR is a stable equivalent of cADPR, which can be useful as a biological tool for investigating cADPR-mediated Ca-mobilizing pathways.