HYDROLYTIC SUSCEPTIBILITIES OF MODIFIED 5'-MESSENGER-RNA CAP ANALOGS TO THE YELLOW LUPIN AP(3)A AND AP(4)A HYDROLASES

Several new dinucleoside tri- and tetraphosphates, 5'-mRNA cap analogu es, have been tested as potential substrates for two enzymes: highly s pecific homogeneous Ap(3)A and (asymmetrical) Ap(4)A hydrolase from ye llow lupin seeds. The AP(3)A hydrolase cleaves all examined dinucleosi de triphosphates yielding in most cases GMP or m(7)GMP and modified di phosphates as the main hydrolysis products (75-100%). Only m(7)Gp(3)G has been hydrolyzed randomly. Compounds with unmodified guanosine have been degraded at comparable rate as natural substrate Ap(3)A. For the analogues modified in guanosine or sugar moiety significant differenc es have been observed in the rate of hydrolysis. Ap(4)A hydrolase seem s to be more specific enzyme than Ap(3)A hydrolase. Dinucleoside tetra phosphates containing guanosine or 7-methylguanosine have been degrade d more slowly than Ap(4)A. In contrast, di- and trimethylated compound s have been hydrolyzed with the rare 2-fold higher in comparison with Ap(4)A. For all methylated dinucleoside tetraphosphates, GTP and methy lated nucleoside monophosphates have been found as the main hydrolysis products