Preparation and characterisation of ribonuclease from human hypertrophic prostate gland (RNAse P2)

Abstract An endo-type, cyclising, 3′-phosphate-forming ribonuclease was purified to homogeneity from a water/Tween 80 extract of human hypertrophic prostate gland. The enzyme is acid- and heat- resistant and is optimally active at pH 7.0, 0.1 M NaCl. Molecular weight determined by gel filtration on Sephadex G-75 and sucrose density gradient centrifugation gave a mean value of 15 000. The prostatic ribonuclease is inhibited by Cu 2+ , bromoacetate and photooxidation in the presence of methylene blue. Other divalent ions, EDTA and p- chloromercuribenzoate have no influence on the enzymic activity. Prostatic RNAse resembles RNAase A in that it preferentially cleaves linkages in RNA after pyrimidine nucleotides to produce oligonucleotides terminated in cyclic 2′,3′ phosphate. The enzyme is inactive with poly(A) · poly(U) as substrate. Poly(U) is hydrolyzed four times as fast as poly(C), and 1.2 times as fast as RNA.