Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Boulevard 113 y 64, 1900 La Plata, Argentina.
J Phys Chem A. 2009 Mar 5;113(9):1794-9. doi: 10.1021/jp8101496.
Steady-state and time-resolved studies of the fluorescence of four aromatic unconjugated pterins (pterin (Ptr), 6-(hydroxymethyl)pterin (Hmp), 6-methylpterin (Mep), and 6,7-dimethylpterin (Dmp)) in aqueous solutions in the presence of different nucleotides (2'-deoxyguanosine 5'-monophosphate (dGMP), 2'-deoxyadenosine 5'-monophosphate (dAMP), and 2'-deoxycytosine 5'-monophosphate (dCMP)) have been performed using the single-photon counting technique. The singlet excited states of acid forms of pterins are deactivated by purine nucleotides (dGMP and dAMP) via a combination of dynamic and static processes. The efficiency of the dynamic quenching is high, independently of the nature of the purine base of the nucleotide and of the chemical structure of the substituents linked to the pterin moiety. Analysis of the static quenching indicates that ground-state association between pterins and purine nucleotides takes place, but the formation of the corresponding complexes is significant only at relatively high reactant concentrations. The quenching of the fluorescence of acid forms of pterin derivatives by dCMP, a pyrimidine nucleotide, is slightly less efficient than the quenching by purine nucleotides and is purely dynamic. In alkaline media, the fluorescence quenching is much less efficient than in acidic media, the deactivation by purine nucleotides being purely dynamic, whereas quenching by dCMP is negligible. Possible mechanisms for the quenching of fluorescence of pterin derivatives by the different nucleotides are discussed.
在存在不同核苷酸（2'-脱氧鸟苷 5'-单磷酸（dGMP）、2'-脱氧腺苷 5'-单磷酸（dAMP）和 2'-脱氧胞苷 5'-单磷酸（dCMP））的水溶液中，使用单光子计数技术对四种芳香非共轭蝶呤（蝶呤（Ptr）、6-（羟甲基）蝶呤（Hmp）、6-甲基蝶呤（Mep）和 6,7-二甲基蝶呤（Dmp））的荧光进行了稳态和时间分辨研究。蝶呤酸形式的单重激发态通过动态和静态过程被嘌呤核苷酸（dGMP 和 dAMP）失活。动态猝灭的效率很高，与核苷酸中嘌呤碱基的性质和与蝶呤部分相连的取代基的化学结构无关。静态猝灭的分析表明，蝶呤和嘌呤核苷酸之间在基态发生了缔合，但只有在反应物浓度相对较高时，才会形成相应的配合物。嘧啶核苷酸 dCMP 对蝶呤衍生物酸形式荧光的猝灭效率略低于嘌呤核苷酸，且仅为动态猝灭。在碱性介质中，荧光猝灭的效率远低于酸性介质，嘌呤核苷酸的失活完全是动态的，而 dCMP 的猝灭可以忽略不计。讨论了不同核苷酸猝灭蝶呤衍生物荧光的可能机制。
