Purification and Properties of a Neutral Endodeoxyribonuclease from Rat Pancreatic Juice

概要

論文の詳細を見る
DNase I was purified from rat pancreatic juice by a procedure including DEAE-cellulose and phosphocellulose chromatographies, Sephadex G-75 gel filtration and concanavalin A-Sepharose affinity chromatography. The purified enzyme contained no detectable activities of acid DNase, acid or alkaline RNase, acid or alkaline phosphatase or nonspecific phosphodiesterase. The molecular weight of the enzyme was estimated to be 37,500 by Sephadex G-75 gel filtration. Its isoelectric point is 4.7+-0.1. The enzyme required divalent cations and shows dual pH optima that are dependent on divalent cations : in the presence of Co2+, the optimum pH is 6.0 in 17 mM cacodylate-HCl buffer and in the presence of Mn2+, the optimum pH is 8.0 in 17 mM Tris-HCl buffer. The enzyme hydrolyzes native DNA about 2 times faster than denatured DNA, producing 5'-phosphoryl and 3'-hydroxyl terminated oligonucleotides with an average chain length of about eight nucleotides. The enzyme converts double-helical pBR322 DNA (form I) to unit length DNA (form III) via open circular DNA (form II). Thus the mode of action of the enzyme is endonucleolytic with single-strand break. The enzyme was inhibited with G-actin of rabbit muscle and antiserum against bovine pancreatic DNase I. The existence of no species-specificity in the inhibition of DNase I enzymes by rabbit muscle actin was considered.
九州大学の論文