Abstract
Nuclease P1 cleaved substantially all phosphodiester bonds in rRNA, tRNA, poly (I), poly (U), poly (A), poly (C), poly (G), poly (I)•poly (C), native DNA and heat-denatured DNA to produce exclusively 5'-mononucleotides. Single-stranded polynucleotides were much more susceptible than double-stranded ones. Influence of pH and ionic strength on the hydrolysis rate significantly varied with the kind of polynucleotides. The enzyme also hydrolyzed 3'-phosphomonoester bonds in 3'-AMP, 3'-GMP, 3'-UMP, 3'-CMP, 3'-dAMP, 3'-dGMP, 3'-dCMP and 3'-dTMP. Ribonucleoside 3'-monophosphates were hydrolyzed 20 to 50 times faster than the corresponding 3'-deoxyribonucleotides. Base preference of the enzyme for 3'-ribonucleotides was in the order of G>A>C_??_U, whereas that for 3'-deoxyribonucleotides was in the order of C_??_T>A_??_G. The 3'-phosphomonoester bonds in nucleoside 3', 5'-diphosphates, coenzyme A and dinucleotides bearing 3'-phosphate were hydrolyzed at a rate similar to that for the corresponding 3'-mononucleotides. Adenosine 2'-monophosphate was highly resistant, being split at less than 1/3, 000 the rate at which 3'-AMP was split.
