The lifetimes and energies of the first excited singlet states of diadinoxanthin and diatoxanthin: the role of these molecules in excess energy dissipation in algae

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• 作者：Frank ; Harry A. ; Cua ; Agnes ; Chynwat ; Veeradej ; Young ; Andrew ; Gosztola ; David ; Wasielewski ; Michael R.
• 关键词：Diadinoxanthin ; Diatoxanthin ; Energy dissipation ; Excited state ; Femtosecond ; Optical spectroscopy ; Xanthophyll cycle
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：1996
• 出版时间：December 18, 1996
• 年：1996
• 卷：1277
• 期：3
• 页码：243-252
• 全文大小：886 K

文摘

The lifetimes of the first excited singlet states (2¹A_g) of diadinoxanthin and diatoxanthin, carotenoids involved in the xanthophyll cycle in some genera of algae, have been measured by femtosecond time-resolved optical spectroscopy to be 22.8 ± 0.1 ps and 13.3 ± 0.1 ps, respectively. Using the energy gap law for radiationless transitions set forth by Englman and Jortner (Mol. Phys. 18 (1970) 145-164), these lifetimes correspond to S₁ excited state energies of 15210 cm⁻¹ for diadinoxanthin and 14620 cm⁻¹ for diatoxanthin. The lowest excited singlet state energy of Chl a has an energy of 14700 cm⁻¹. The fact that the S₁ state energy of diadinoxanthin lies above that of Chl a, whereas the S₁ state energy of diatoxanthin lies below that of Chl a, suggests that the xanthophyll cycle involving the enzymatic interconversion of diadinoxanthin and diatoxanthin may play a role in regulating energy flow between these molecules and Chl a in many species of algae, essentially fulfilling a role identical to that proposed for violaxanthin and zeaxanthin in higher plants and green algae (Frank et al. (1994) Photosyn. Res. 41, 389-395).