The chromophore structural changes during the photocycle of phytochrome: A combined resonance raman and quantum chemical approach

MROGINSKI, M.A.; MURGIDA, D.H.; HILDEBRANDT, P.

ACCOUNTS OF CHEMICAL RESEARCH

AMER CHEMICAL SOC

Año: 2007 vol. 40 p. 258 - 266

0001-4842

Phytochromes are sensory photoreceptors that, upon light irradiation, can be transformed between an inactive and an active state. The conversion is initiated by the photoisomerization of the cofactor, a linear methine-bridged tetrapyrrole, followed by conformational relaxations of the chromophore and the protein matrix that finally leads to the formation of the signaling state. To elucidate the underlying molecular processes, resonance Raman spectroscopy combined with quantum chemical calculations constitutes a powerful approach since it allows determination of the chromophore structure in the various states of phytochrome. On the basis of these studies, a molecular model for the photoinduced reaction cycle is derived. Phytochromes are sensory photoreceptors that, upon light irradiation, can be transformed between an inactive and an active state. The conversion is initiated by the photoisomerization of the cofactor, a linear methine-bridged tetrapyrrole, followed by conformational relaxations of the chromophore and the protein matrix that finally leads to the formation of the signaling state. To elucidate the underlying molecular processes, resonance Raman spectroscopy combined with quantum chemical calculations constitutes a powerful approach since it allows determination of the chromophore structure in the various states of phytochrome. On the basis of these studies, a molecular model for the photoinduced reaction cycle is derived.