Herein, a novel fluorescent nucleotide analogue, perylene-2′-amino-α-L-LNA, has been prepared and studied within synthetic oligonucleotides of different sequences. The phosphoramidite reagent was synthesized in 85% overall yield starting from 2′-amino-α-L-LNA nucleoside. Incorporation efficiency of the resulting perylene-2′-amino-α-L-LNA monomer (T*) into synthetic oligonucleotides was significantly improved by replacement of the typically used 1H-tetrazole activator with pyridine hydrochloride. Generally, oligonucleotides containing monomerT* showed high binding affinity towards complementary DNA and RNA targets, batochromically shifted excitation/emission wavelengths with respect to the often applied polyaromatic hydrocarbon pyrene, high fluorescent quantum yields and very low target detection limits (5–10 nM). Fluorescence of single stranded LNA/DNA mixmer oligonucleotide having two incorporations of monomersT* was quenched (quantum yield ΦF= 0.21) relative to duplexes of this probe with complementary DNA and RNA (ΦF= 0.42 and 0.35, respectively). On the contrary, a strong fluorescence quenching upon target binding was demonstrated by two short oligonucleotides of analogues sequences containing monomersT* at 5′- and 3′-terminal positions. We explain the hybridization-induced light-up effect observed for double-labeled probe by a reduction of fluorescence quenching due to precise positioning of the fluorophores within the double-stranded complexes. Furthermore, we propose that a covalent link between twoT* monomers in the double-labeled probe provides a remarkable degree of rigidity in the double helix which enforces positioning of the bulky perylene moieties in the nonpolar groove resulting in reduced fluorescence quenching.
本文报道了一种新型荧光核苷酸类似物——perylene-2'-amino-α-L-LNA,其在不同序列的合成寡核苷酸中得到了研究。该磷酸酰胺试剂以2'-氨基-α-L-LNA核苷为起始物,在总收率85%的情况下合成。通过用吡啶盐酸盐代替通常使用的1H-四唑活化剂,显著提高了perylene-2'-amino-α-L-LNA单体(T*)在合成寡核苷酸中的插入效率。通常,含有单体T*的寡核苷酸对互补的DNA和RNA靶点表现出高结合亲和力,相对于通常应用的多芳香族碳氢化合物芘,显示出巴托克移的激发/发射波长,高荧光量子产率和非常低的靶点检测限制(5-10 nM)。含有两个单体T*插入的单链LNA/DNA混合物寡核苷酸的荧光被猝灭(量子产率ΦF = 0.21),相对于该探针与互补DNA和RNA的双链体(ΦF = 0.42和0.35,分别)相比。相反,两个类似序列的短寡核苷酸中,含有单体T*在5'-和3'-末端位置,与靶标结合时表现出强烈的荧光猝灭。我们通过精确定位双链复合物内荧光团分子的减少荧光猝灭来解释双标记探针的杂交诱导的增强效应。此外,我们提出,在双标记探针中,两个T*单体之间的共价键提供了双螺旋结构中的显著刚度,强制使得笨重的perylene基团位于非极性沟槽中,从而导致荧光猝灭减少。