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Molecular interactions of the redox‐active accessory chlorophyll on the electron‐donor side of photosystem II as studied by Fourier transform infrared spectroscopy
Author(s) -
Takumi Noguchi,
Yorinao Inoue
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00833-u
Subject(s) - chemistry , photosystem ii , p700 , fourier transform infrared spectroscopy , infrared , redox , photochemistry , light harvesting complexes of green plants , photosystem i , infrared spectroscopy , chlorophyll , chlorophyll a , hydrogen bond , photosynthesis , molecule , inorganic chemistry , biochemistry , organic chemistry , physics , quantum mechanics , optics
A Fourier transform infrared (FTIR) difference spectrum upon photooxidation of the accessory chlorophyll (Chl z ) of photosystem II (PS II) was obtained at 210 K with Mn‐depleted PS II membranes in the presence of fericyanide and silicomolybdate. The observed Chl z + /Chl z spectrum showed two differential bands at 1747/1736 and 1714/1684 cm − . The former was assigned to the free carbomethoxy C = 0 and the latter to the keto C = 0 that is hydrogen‐bonded or in a highly polar environment. Also, the negative 1614 cm − band assignable to the macrocycle mode indicated 5‐coordination of the central Mg. The negative 1660 cm −1 band, possibly due to the strongly hydrogen‐bonded keto C = 0, may suggest oxidation of one more Chl z , although an alternative assignment, the amide I mode of proteins perturbed by Chl z oxidation, is also possible.