EQUILIBRIUM STUDIES OF ETHIDIUM-POLYNUCLEOTIDE INTERACTIONS
EQUILIBRIUM STUDIES OF ETHIDIUM-POLYNUCLEOTIDE INTERACTIONS
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DOI：
10.1021/bi00515a038
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发表时间：
1981-01-01
期刊：
影响因子：
2.9
通讯作者：
CROTHERS, DM
中科院分区：
文献类型：
--
作者：
BRESLOFF, JL;CROTHERS, DM
本文报道了用平衡透析法研究乙锭与各种含有A·U（或T）和I·C碱基对的双螺旋合成多核苷酸的结合。结果被解释的邻居排斥模型的药物结合，与津贴的协同性的结合和螺旋的结构切换到一个不同的形式，结合药物更有效。DNA和所检测的交替共聚物[poly[d（A-T）]和poly[d（I-C）]]在1 M盐中显示出高亲和力（104-105 M-1）。同聚多核苷酸显示出更复杂的亲和性模式：poly（rA）·cnt·poly（rU）、poly（rA）·cnt·poly（dT）和poly（dA）·cnt·poly（rU）显示出高亲和性，而poly（dA）·cnt·poly（dT）、poly（rI）·cnt·poly（rC）和poly（dI）·cnt·poly（dC）显示出低亲和性（≤103 M-1）。DNA或B家族螺旋的排除范围为2个碱基对，RNA或A家族螺旋的排除范围为3个碱基对。通常，多核苷酸在它们的乙锭结合中显示出一定的协同性。数据揭示了聚[d（I-C）]转变为能够更有效地结合乙锭的形式。
Equilibrium dialysis studies of the binding of ethidium to a variety of double-helical synthetic polynucleotides containing A.cntdot.U (or T) and I.cntdot.C base pairs are reported. The results are interpreted in terms of the neighbor exclusion model of drug binding, with allowance both for cooperativity of binding and for a structural switch of the helix to a different form which binds the drug more effectively. Both DNA and the alternating copolymers examined [poly[d(A-T)] and poly[d(I-C)]] showed high affinity (104-105 M-1) in 1 M salt. Homopolynucleotides showed a more complicated pattern of affinities: poly(rA).cntdot.poly(rU), poly(rA).cntdot.poly(dT), and poly(dA).cntdot.poly(rU) showed high affinity, whereas poly(dA).cntdot.poly(dT), poly(rI).cntdot.poly(rC), and poly(dI).cntdot.poly(dC) showed low affinity (.ltoreq. 103 M-1). Theneighbor exclusion range was inferred to be 2 base pairs for DNA or B family helices and 3 for RNA or A family helices. Generally, polynucleotides showed some cooperativity in their ethidium binding. The data reveal a switch of poly[d(I-C)] to a form able to bind ethidium more effectively.