含单个色氨酸的多肽分子的荧光特性研究:pH及金属离子的响应

由于金属离子包括铜离子对人体的重要性,报道了一种含单个色氨酸的新型多肽分子(WDAHSS),证明利用这种分子可以通过荧光光谱测量的方法实现铜离子灵敏检测。WDAHSS的荧光由其包含的色氨酸残基的本征荧光贡献,易被铜离子猝灭。通过分析铜离子在不同pH值条件下与WDAHSS作用的荧光光谱并与单个色氨酸分子的光谱相比较,详细研究了铜离子猝灭WDAHSS荧光的机理。研究表明,WDAHSS结构中的组氨酸通过金属配位与铜离子作用,并联合肽键形成稳固的四方形平面结构,螯合铜离子,致使色氨酸残基发生荧光猝灭。同时详细讨论了不同pH值环境对WDAHSS荧光光谱的影响。通过荧光光谱测量和数值拟合,推测了WDAHSS和铜离子的结合常数。为了增强WDAHSS抗pH干扰的能力,特意对其氨基端乙酰化,在生理pH值范围内稳定了其荧光发射。此外,WDAHSS也采用了一些特殊设计的结构,很好地增强了它对铜离子灵敏探测的特异选择性和生物相容性。对WDAHSS的进一步研究有望用于生物体内或细胞内荧光成像检测。

Fluorescence Properties of Single-Trp Peptide: Response to pH and Metal Ions

Considering the important role of metal ions inc luding copper ions are playing in human body,a novel single-Trp peptide WDAHSS was designed and synthesized in this study to achieve sensitive detection of co pper ions via fluorescence spectroscopy.The intrinsic fluorescence of a tryptop han residue in WDAHSS,which was the only source of the molecular fluorescence,could be easily quenched with copper ions.By comparing fluorescence spectra of WDAHSS with those of tryptophan molecules at different pH values,the quenching mechanism of WDAHSS was explored in detail.Research showed that the histidine i n WDAHSS bound copper ions with metal coordination.With participation of peptid e bond,a square planar structure was formed.It was a consequent chelation of c opper ions that caused the quenching of tryptophan residue.At the same time,th is study discussed how pH conditions affected the fluorescence spectra of WDAHSS.Furthermore,association constants of copper ions towards WDAHSS were calculat ed through fluorescence measurements and fitting analyses.To enhance the antijamming ability to pH variation,the amino terminal of WDAHSS was intentionally acetylized,leading to a stable fluorescence emission under physiological pH con ditions.Besides,WDAHSS was designed as a special structure to enhance the sele ctivity and biocompatibility of its sensitive detection of copper ions.F urther studies on WDAHSS may help to improve the fluorescence imaging detection in vivo.