STUDY OF HYDROLYTIC ACTIVITIES OF THREE COMPONENT COMPLEXES OF DNA・LIGANDS・METAL ION

金属离子对磷酰和核苷酸水解和转移反应的影响一直是一个长期的广泛关注的课题。研究了金属配合物对UTP（ATP和UTP）的定点水解作用。本文合成并研究了2，2 ′-二吡啶胺（dpa）衍生物（L），其中dpa通过不同长度的亚甲基间隔基与腺嘌呤、胸腺嘧啶和鸟嘌呤连接，在pH7.3、40 ℃下水解ATP和UTP 24 h，水解量分别为1.2%和1.2%。（NDP和NMP）通过阴离子交换HPLC监测。1化学计量的Cu（L）^<2+>、含腺嘌呤配体的配合物，在这两项活动中均表现为上级（水解%）和位点选择性（ADP/AMP和UDP/UMP的比率）与单独的其他二价金属离子（Cu^2+、Mg^2+、Zn^2+和Ni^2+）或它们的M（L）^2+-络合物相比。Cu（L）^<2+>-配合物表现出优先裂解末端的γ-磷酸基团，尽管这些配体的活性中心Cu（dpa）^<2+>抑制它们的水解。这些复合物的反应性和它们的间隔基长度的影响表明ATP或UTP与配体之间的碱基-碱基部分的相互作用。本文用~ 1H-NMR和~ 1H-NMR研究了Zn^&lt;2+&gt;：L：ATP三元配合物的形成<31>。作为DNA切割试剂，研究了这些M^&lt;2+&gt;-配体配合物对质粒DNA（pCU 18）的切割活性，发现含腺嘌呤配体的Zn（L）^&lt;2+&gt;配合物是有效的（超螺旋质粒DNA（I型）水解为切口DNA（II型）和线性DNA（III型），电泳后测定），并表明可作为一种区域酶的模型。

Metal ion effects on the phosphoryl and nucleotidyl hydrolyses and transfer reactions have been a long lasting subject of broad interests. We studied the site-selective hydrolyses of UTPs (ATP and UTP) promoted by metallo-complexes of appropriate ligands. The ligands (L) synthesized and examined were 2,2'-dipyridylamine (dpa) derivatives in which dpa is linked to adenine, thymine, and guanine mojities with a methylene-spacer of different lengths.The hydrolyses of ATP and UTP were carried out at pH 7.3 and 40ﾟC for 24 h and the amounts of the hydrolyses (NDP and NMP) were monitored by an anion-exchange HPLC.The 1 : 1 stoichiometric complexes of Cu(L)^<2+>, adenine containing ligand, were found to be superior in both the activities (hydrolyses %) and site-selectivities (ratios of ADP/AMP and UDP/UMP) as compared to other divalent metal ions (Cu^<2+>, Mg^<2+>, Zn^<2+> and Ni^<2+>) alone or their M (L) ^<2+>-complexes. The Cu(L)^<2+>-complexes showed the preferential cleavages of the terminal gamma-phosphate groups, although Cu(dpa)^<2+>, the active site of these ligands, inhibited their hydrolyses. The effect of reactivities of these complexes and their spacer-lengths suggests the interactions of the base-base moieties between ATP or UTP and the ligands. The formation of the ternary complex of Zn^<2+> : L : ATP was studies by using ^1H-and ^<31>P- NMR spectra. The hydrolytic activities of other ligands are investigated now.As DNA cleaving reagents, these M^<2+>-ligand complexes were examined to investigate their reactivities for thecleavages of plasmide DNA (pCU 18) and the Zn(L)^<2+> complexes, ademine containing ligand, were found to be effective (supercoil plasmide DNA (Form I) hydrolyzed to nicked (Form II) and linear DNA (Form III), measured after electrophyrisis) and indicated to work as a kind of models of distriction enzymes.