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Soret absorption of intermediate(s) in protochlorophyllide to chlorophyllide photoreduction trapped at low temperature
Author(s) -
Dujardin Esther,
Kahn Albert,
Mathis Paul
Publication year - 1990
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1990.tb08725.x
Subject(s) - protochlorophyllide , photochemistry , avena , chemistry , phaseolus , absorption (acoustics) , fluorescence , etiolation , chlorophyll , hordeum vulgare , botany , biology , biochemistry , materials science , chloroplast , poaceae , organic chemistry , optics , enzyme , physics , composite material , gene
Absorption spectra at ca 100 K from 400 to 750 nm and fluorescence emission spectra at 77 K from 600 to 750 nm were obtained from: 1) etiolated leaves of the H‐ordeum vulgare L. (barley) mutant albozonata 2 and SAN 9789‐treated Avena sativa L. (oat) with low levels of carotenoids, and 2) preparations of protochlorophyllide holo‐chrome from Phaseolus vulgaris L. cv. Commodore (bean). This allowed clear resolution for the first time of the Soret bands of the green pigments before and after light‐induced accumulation of intermediate(s) in protochlorophyllide to chlorophyllide photoreduction and after conversion of the intermediate(s) to chlorophyllide by warming the samples to 233 K in darkness. Although the intermediate(s) differ(s) in absorption and fluorescence in the red wavelength region from both protochlorophyllide and chlorophyllide, the extinction in the Soret band is not distinguishable from that of chlorophyllide. These observations indicate that the C7‐C8 double bond in ring IV of protochlorophyllide has been altered in intermediate(s) accumulated at low temperature in intense light, such that the transition state exhibits the character of a π complex.