2 DEOXYRIBONUCLEASES K1 AND K2 ISOLATED FROM MYCELIA OF ASPERGILLUS ORYZAE .2. DETERMINATION OF 5'- AND 3'-TERMINI OF DNA FRAGMENTS PRODUCED BY DNASES K1 AND K2

The DNA fragments produced from calf thymus DNA by treatment with DNases K1 and K2 were studied.1. The K1 digest gave deoxyguanosine and deoxyadenosine when treated with venom phosphodiesterase [EG 3.1.4.1] and deoxyguanosine when treated with alkaline phosphatase [EC 3.1.3.1] and spleen phosphodiesterase [EC 3.1.4.1]. It was presumed that DNase Kl might preferentially split the phosphodiester-bonds between dG and dG and between dG and dA at the 5'side giving as the products oligo- and poly-nucleotides with 3' terminal phosphate.2. The K2 digest was studied by similar methods. DNase K2 seems to split preferentially the above mentioned bonds at the 3'side giving as the products oligo- and poly-nucleotides with 5' terminal phosphate.3. The K1 and K2 digests were fractionated on DEAE-cellulose columns. The digests consisted of single and double stranded DNA fragments with various molecular size. The large DNA fragments were comparatively poor in G.4. When a double stranded DNA fraction from the K2 digest was digested with an enzyme which specifically splits single stranded portion, there appeared a large percentage of 5' deoxyguanylic acid. The non-digestible portion showed hyperchromism. It was presumed that the DNA fraction might consist of a double stranded portion and a single stranded portion. © 1968 by the Journal of Biochemistry.