뱀독 phosphodiesterase의 endonuclease 활성에 대한 pUC19 DNA의 절단부위를 확인하였다. Phosphodiesterase의 endonuclease 반응에 의하여 supercoil 형태의 pUC19은 linear형태 이외에 1579 bp와 1107 bp의 DNA 단편들로 분해된다. 제한효소 mapping 분석방법으로 결정한 pUC19의 절단부위는 1398과 2505였다. Cruciform을 이루고 있는 1398 위치의 절단부위는 single-strand specific nuclease S1의 작용부위와 일치하는 것으로 밝혀졌으며 2505 위치는 hairpin 구조를 이루는 것으로 예상된다. 그러므로 뱀독 phosphodiesterase의 endonuclease 활성은 DNA의 cruciform 또는 (A+T)-rich hairpin 구조를 인식하여 가수분해함을 증명하였다.
Endonucleolytic cleavage sites of pUC19 by snake venom phosphodiesterase were identified. Limited digestion of supercoiled pUC19 DNA by the phosphodiesterase yields unit length linear form of the plasmid plus two discrete fragments which are 1579 by and 1107 bp. Studies of restriction enzyme mapping analysis indicate that the cleavage sites are 1398 and 2505 of pUC19. The cleavage site located at 1398 which is known as a cruciform structure, coincides with the position recognized by single-strand specific nuclease S1. The 2505 region appears to form a hairpin structure with (A+T)-rich sequence. It is concluded that the endonuclease activity of snake venom phophodiesterase recognizes certain specific secondary structures such as cruciform or (A+T)-rich hairpin region of DNA.
