Nygren J, Svanvik N, Kubista M
Department of Biochemistry and Biophysics Lundberg Institute, Chalmers University of Technology, Göteborg, Sweden.
Biopolymers. 1998 Jul;46(1):39-51. doi: 10.1002/(SICI)1097-0282(199807)46:1<39::AID-BIP4>3.0.CO;2-Z.
The interaction of the fluorescent dye thiazole orange (TO) with nucleic acids is characterized. It is found that TO binds with highest affinity to double-stranded (ds) DNA [log (K) approximately 5.5 at 100 mM salt], about 5-10 times weaker to single-stranded polypurines, and further 10-1000 times weaker to single-stranded polypyrimidines. TO binds as a monomer to dsDNAs and poly(dA), both as a monomer and as a dimer to poly(dG) and mainly as a dimer to poly(dC) and poly(dT). The fluorescence quantum yield of TO free in solution is about 2 x 10(-4), and it increases to about 0.1 when bound to dsDNA or to poly(dA), and to about 0.4 when bound to poly(dG). Estimated quantum yields of TO bound to poly(dC) and poly(dT) are about 0.06 and 0.01, respectively. The quantum yield of bound TO depends on temperature and decreases about threefold between 5 and 50 degrees C.
对荧光染料噻唑橙（TO）与核酸的相互作用进行了表征。结果发现，TO与双链（ds）DNA的结合亲和力最高[在100 mM盐浓度下，log（K）约为5.5]，与单链聚嘌呤的结合力约弱5至10倍，与单链聚嘧啶的结合力则进一步弱10至1000倍。TO以单体形式与dsDNA和聚（dA）结合，与聚（dG）结合时既可以单体形式也可以二聚体形式存在，而与聚（dC）和聚（dT）结合时主要以二聚体形式存在。溶液中游离的TO的荧光量子产率约为2×10⁻⁴，与dsDNA或聚（dA）结合时增加到约0.1，与聚（dG）结合时增加到约0.4。估计TO与聚（dC）和聚（dT）结合时的量子产率分别约为0.06和0.01。结合态TO的量子产率取决于温度，在5至50摄氏度之间会降低约三倍。
