Purification of a Nuclease from Penicillium citrinum

Abstract A nuclease was purified about 1500-fold with a recovery of 20% from an aqueous extract of culture of a pigmentless mutant VI–10–14 of Penicillium citrinum on wheat bran. The purified preparation was homogeneous on the basis of the criteria of ultracentrifugation and disc gel electrophoresis. The preparation was essentially free of 5′-nucleotidase, non-specific phosphomonoesterase, non-specific phosphodiesterase and 3′-monoester forming nuclease. The preparation hydrolyzed phosphodiester bonds in RNA and DNA to yield 5′-mononucleotides, and also the phosphomonoester bond in 2′- and 3′-AMP to yield nucleoside and inorganic phosphate. The enzyme activities toward these substrates were not separated and relative ratio of their specific activities remained constant throughout the purification, suggesting that a single enzyme was responsible for these activities.