Studies on a nuclease from Penicillium citrinum. VIII. Comparison of nuclease P1-malonogalactan complex with nuclease P1.

Abstract

Properties of nuclease P1-malonogalactan complex (P1-MG) were compared with those of the polysaccharide-free nuclease P1. Significant difference was not observed between them in phosphomonoester splitting activity, but marked differences were observed in nucleolytic activity as follows: (1) The pH optima of P1-MG for RNA and heat-denatured DNA were lower than those of nuclease P1. (2) At lower than 0.001 of ionic strength, RNA and heatdenatured DNA were attacked hardly by P1-MG, but attacked well by nuclease P1. (3) The increase in hydrolysis rate of RNA or heat-denatured DNA with an elevation of temperature from 37°C to 70°C was not so marked in P1-MG as compared with nuclease P1. (4) P1-MG hydrolyzed polynucleotides, especially native DNA, much slower than nuclease P1. Influence of ionic strength, pH and temperature on the nucleolytic activity of nuclease P1-galactan (P1-G), which was prepared by demalonylating P1-MG enzymatically, was similar to that of nuclease P1, except that the activity of P1-G for native DNA was much lower than nuclease P1.