Krynetskaya N F, Kubareva E A, Timchenko M A, Belkov V M, Shabarova Z A
School of Chemistry, Lomonosov Moscow State University, Moscow, 119899, Russia.
Biochemistry (Mosc). 1998 Sep;63(9):1068-73.
A 30-membered DNA duplex containing the recognition site of restriction endonuclease SsoII and a 30-membered RNA--DNA hybrid duplex, a substrate of E. coli RNase H, were synthesized. The cleavage of the 30-membered fragments of nucleic acids catalyzed by endonucleases in the presence of Co-phthalocyanine complex [CoPc(COONa)8] containing eight carboxyl groups at the periphery of the ligand was studied. It was shown that the efficiency of enzyme catalysis decreases in the presence of the metal complex for both endonucleases. By addition of a 100-fold excess of Co-phthalocyanine complex with respect to DNA duplex the initial rate of substrate hydrolysis by restriction endonuclease SsoII is observed to decrease twice. An equimolar ratio of the metal complex and hybrid duplex leads to essentially complete inhibition of RNA cleavage by RNase H from E. coli. The inhibition of catalytic activity of enzymes recognizing the double-stranded nucleic acids in the presence of Co-phthalocyanine complex is assumed to be caused by the ability of the latter to interact with DNA, RNA, and DNA--RNA duplexes.
合成了包含限制性内切核酸酶SsoII识别位点的30元DNA双链体以及作为大肠杆菌RNase H底物的30元RNA-DNA杂交双链体。研究了在配体外围含有八个羧基的钴酞菁配合物[CoPc(COONa)8]存在下，核酸内切酶催化30元核酸片段的切割情况。结果表明，对于这两种核酸内切酶，在金属配合物存在下酶催化效率均降低。相对于DNA双链体加入100倍过量的钴酞菁配合物，观察到限制性内切核酸酶SsoII对底物水解的初始速率降低了两倍。金属配合物与杂交双链体的等摩尔比导致大肠杆菌RNase H对RNA切割的基本完全抑制。钴酞菁配合物存在下对识别双链核酸的酶催化活性的抑制被认为是由于后者与DNA、RNA和DNA-RNA双链体相互作用的能力所致。
