a comparison of the two thiopurine cyclic nucleotides with their nucleoside counterparts has suggested that ( a ) the thio derivatives act by a common mechanism which is different from that exerted by the methylthio derivatives , and ( b ) the methylthio cyclic nucleotide acts , at least in part , by a mechanism which differs from that exerted by the methylthio nucleoside .
C0028631
cyclic nucleotides
C0028630
nucleotide