Time-Resolved Fluorescence of Water-Soluble Pyridinium Salt: Sensitive Detection of the Conformational Changes of Bovine Serum Albumin.
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.
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Lei
L
Li
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Hua
H
Yi
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Menghui
M
Jia
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Mengfang
M
Chang
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Zhongneng
Z
Zhou
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.
Sanjun
S
Zhang
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Haifeng
H
Pan
Tongji Hospital Affiliated to Tongji University, Shanghai, China.
Yan
Y
Chen
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Jinquan
J
Chen
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China Collaborative Innovation Centre of Extreme Optics, Shanxi University, Taiyuan, China.
Jianhua
J
Xu
4-[2-(4-Dimethylamino-phenyl)-vinyl]-1-methylpyridinium iodide (p-DASPMI); Fluorescence probe; Time-resolved fluorescence (TRF); bovine serum albumin (BSA)