Kinetics of and intermediates in a photocycle branching reaction of the photoactive yellow protein from Ectothiorhodospira halophila

FEBS Letters

Hellingwerf, Klaas J.¹  Hendriks, Johnny¹  Crielaard, Wim¹  van Stokkum, Ivo H.M.² 

[1] Laboratory for Microbiology, E.C. Slater Institute, BioCentrum, University of Amsterdam, Nieuwe Achtergracht 127, 1018 WS Amsterdam, The Netherlands;Department of Physics Applied Computer Science, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands

关键词: Transient spectroscopy;    Photocycle intermediate;    Branching reaction;    Blue light;    Photoactive yellow protein;    Global analysis;    PYP;    photoactive yellow protein;    pG;    dark-adapted ground state photocycle intermediate of PYP;    pR;    red-shifted photocycle intermediate of PYP;    pB;    blue-shifted photocycle intermediate of PYP;    pBt;    blue-shifted intermediate formed after UVA light absorption by pB;   

DOI  :  10.1016/S0014-5793(99)01136-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have studied the kinetics of the blue light-induced branching reaction in the photocycle of photoactive yellow protein (PYP) from Ectothiorhodospira halophila, by nanosecond time-resolved UV/Vis spectroscopy. As compared to the parallel dark recovery reaction of the presumed blue-shifted signaling state pB, the light-induced branching reaction showed a 1000-fold higher rate. In addition, a new intermediate was detected in this branching pathway, which, compared to pB, showed a larger extinction coefficient and a blue-shifted absorption maximum. This substantiates the conclusion that isomerization of the chromophore is the rate-controlling step in the thermal photocycle reactions of PYP and implies that absorption of a blue photon leads to cis→trans isomerization of the 4-hydroxy-cinnamyl chromophore of PYP in its pB state.

【 授权许可】

Unknown