We report herein the uracil-di-aza-amino acid (U^rAA) as a new family of molecular scaffold to induce β-hairpin structure with H-bonded β-sheet conformation in a short peptide. This has been demonstrated in two conceptual fluorescent pentapeptides wherein triazolylpyrenyl alanine and/or triazolylmethoxynapthyl alanine (^TPyAla_Do and/or ^TMNapAla_Do) are embedded into two arms of the uracil-amino acid via an intervening leucine. Conformational analysis by CD, IR, variable temperature and 2D NMR spectroscopy reveals the β-hairpin structures for both the peptides. Study of photophysical property reveals that the pentapeptide containing fluorescent triazolyl unnatural amino acids ^TMNapAla_Do and ^TPyAla_Do at the two termini exhibits dual path entry to exciplex emission-either via FRET from ^TMNapAla_Do to ^TPyAla_Do or via direct excitation of a FRET acceptor, ^TPyAla_Do. The other pentapeptide with ^TPyAla_Do/^TPyAla_Do pair shows excimer emission. Furthermore, both the peptides maintaining their fundamental photophysics are found to interact with BSA as only a test biomolecule.

我们在此报告尿嘧啶二氮杂-氨基酸（Ú ^ř AA）作为新的家族分子骨架的诱导β发夹用H-β结合片层构象结构的短肽。这已经在两个概念性荧光五肽中得到证实，其中三唑基^吡啶基丙氨酸和/或三唑基^甲氧基^萘基丙氨酸（^TPy Ala _Do和/或^TMNap Ala _Do）通过中间亮氨酸被嵌入到尿嘧啶氨基酸的两个臂中。通过CD，IR，可变温度和2D NMR光谱进行的构象分析揭示了两种肽的β-发夹结构。光物理性质的研究表明，五肽中含有荧光三唑基非天然氨基酸在两个末端的^TMNap Ala _Do和^TPy Ala _Do表现出向激基复合物发射的双路径进入-通过从^TMNap Ala _Do到^TPy Ala _Do的FRET或通过FRET受体^TPy Ala _Do的直接激发。另一对具有^TPy Ala _Do / ^TPy Ala _Do的五肽显示了受激准分子发射。此外，发现两种维持其基本光物理性质的肽都仅作为测试生物分子与BSA相互作用。