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Appl Spectrosc. 2016 Oct 1;70(10):1733-1738. Epub 2016 Jun 20.

Time-Resolved Fluorescence of Water-Soluble Pyridinium Salt: Sensitive Detection of the Conformational Changes of Bovine Serum Albumin.

Author information

1
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
2
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China Collaborative Innovation Centre of Extreme Optics, Shanxi University, Taiyuan, China sjzhang@phy.ecnu.edu.cn.
3
Tongji Hospital Affiliated to Tongji University, Shanghai, China.
4
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China Collaborative Innovation Centre of Extreme Optics, Shanxi University, Taiyuan, China.

Abstract

In this paper, we report a pyridinium salt "turn-on" fluorescent probe, 4-[2-(4-Dimethylamino-phenyl)-vinyl]-1-methylpyridinium iodide (p-DASPMI), and applied its time-resolved fluorescence (TRF) to monitor the protein conformational changes. Both the fluorescence lifetime and quantum yield (QY) of p-DASPMI were increased about two orders of magnitude after binding to the protein bovine serum albumin (BSA). The free p-DASPMI in solution presents an ultrashort fluorescence lifetime (12.4 ps), thus it does not interfere the detection of bound p-DASPMI which has nanosecond fluorescence lifetime. Decay-associated spectra (DAS) show that p-DASPMI molecules bind to subdomains IIA and IIIA of BSA. The TRF decay profiles of p-DASPMI can be described by multi-exponential decay function ([Formula: see text]), and the obtained parameters, such as lifetimes ([Formula: see text]), fractional amplitudes ([Formula: see text]), and fractional intensities ([Formula: see text]), may be used to deduce the conformational changes of BSA. The pH and Cu2+ induced conformational changes of BSA were investigated through the TRF of p-DASPMI. The results show that the p-DASPMI is a candidate fluorescent probe in studying the conformational changes of proteins through TRF spectroscopy and microscopy in the visible range.

KEYWORDS:

4-[2-(4-Dimethylamino-phenyl)-vinyl]-1-methylpyridinium iodide (p-DASPMI); Fluorescence probe; Time-resolved fluorescence (TRF); bovine serum albumin (BSA)

PMID:
27324423
DOI:
10.1177/0003702816644609

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