Picosecond Dynamics of G-Protein Coupled Receptor Activation in Rhodopsin from Time-Resolved UV Resonance Raman Spectroscopy
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- 作者：Judy E. Kim ; Duohai Pan ; and Richard A. Mathies
- 刊名：Biochemistry
- 出版年：2003
- 出版时间：May 13, 2003
- 年：2003
- 卷：42
- 期：18
- 页码：5169 - 5175
- 全文大小：174K
- 年卷期：v.42,no.18(May 13, 2003)
- ISSN：1520-4995
文摘
The protein response to retinal chromophore isomerization in the visual pigment rhodopsin isstudied using picosecond time-resolved UV resonance Raman spectroscopy. High signal-to-noise Ramanspectra are obtained using a 1 kHz Ti:Sapphire laser apparatus that provides <3 ps visible (466 nm)pump and UV (233 nm) probe pulses. When there is no time delay between the pump and probe events,tryptophan modes W18, W16, and W3 exhibit decreased Raman scattering intensity. At longer pump-probe time delays of +5 and +20 ps, both tryptophan (W18, W16, W3, and W1) and tyrosine (Y1 +2xY16a, Y7a, Y8a) peak intensities drop by up to 3%. These intensity changes are attributed to decreasedhydrophobicity in the microenvironment near at least one tryptophan and one tyrosine residue that likelyarise from weakened interaction with the 
-ionone ring of the chromophore following cis-to-transisomerization. Examination of the crystal structure suggests that W265 and Y268 are responsible forthese signals. These UV Raman spectral changes are nearly identical to those observed for the rhodopsin-to-Meta I transition, implying that impulsively driven protein motion by the isomerizing chromophoreduring the 200 fs primary transition drives key structural changes that lead to protein activation.
-ionone ring of the chromophore following cis-to-transisomerization. Examination of the crystal structure suggests that W265 and Y268 are responsible forthese signals. These UV Raman spectral changes are nearly identical to those observed for the rhodopsin-to-Meta I transition, implying that impulsively driven protein motion by the isomerizing chromophoreduring the 200 fs primary transition drives key structural changes that lead to protein activation.