Hyun K M, Choi S D, Lee S, Kim S K
Department of Chemistry, College of Sciences, Yeungnam University, Kyoungsan City, South Korea.
Biochim Biophys Acta. 1997 Mar 15;1334(2-3):312-6. doi: 10.1016/s0304-4165(96)00111-0.
Contact energy transfer from DNA bases to various ligands, which can be represented by the ratio of the fluorescence intensity Q(lambda)/Q310nm, is measured by conventional fluorometer. 4',6-Diamidino-2-phenylindole and 2'-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5'-bi-1H-benzimidazole can accept energy from DNA bases and exhibit the ratio Q(lambda)/Q310nm, similar to that of intercalators, although these molecules are known to bind preferentially to the minor groove of the adenine-thymine rich region of DNA. When porphyrin is intercalated in DNA or poly[d(G-C)2], the shape of the ratio Q(lambda)/Q310nm is distinct from that of the ethidium-DNA complex with two maxima at 250 nm and 280 nm. The ratio Q(lambda)/Q310nm of the porphyrin-poly[d(A-T)2] complex, in which porphyrin is known to bind 'outside' of the DNA stem, is similar to that of intercalators. Therefore, energy from excited DNA bases can be transferred not only to an intercalated ligand through direct contact but also to that bound in the minor groove. It follows from this observation that using energy transfer as a criterion for DNA intercalation requires extreme caution.
通过传统荧光计测量从DNA碱基到各种配体的接触能量转移，其可以用荧光强度比Q(λ)/Q310nm来表示。4',6-二脒基-2-苯基吲哚和2'-(4-羟基苯基)-5-(4-甲基-1-哌嗪基)-2,5'-联-1H-苯并咪唑可以从DNA碱基接受能量，并呈现出与嵌入剂相似的Q(λ)/Q310nm比值，尽管已知这些分子优先结合于富含腺嘌呤-胸腺嘧啶区域的DNA小沟。当卟啉嵌入DNA或聚[d(G-C)2]中时，Q(λ)/Q310nm比值的形状与溴化乙锭-DNA复合物不同，后者在250nm和280nm处有两个最大值。已知卟啉结合在DNA链“外部”的卟啉-聚[d(A-T)2]复合物的Q(λ)/Q310nm比值与嵌入剂相似。因此，激发态DNA碱基的能量不仅可以通过直接接触转移到嵌入的配体上，也可以转移到结合在小沟中的配体上。由此观察结果可知，将能量转移用作DNA嵌入的标准需要极其谨慎。
