An Ascorbate-induced Absorbance Change in Chloroplasts from Violaxanthin De-epoxidation 1

AUTOR(ES)

Yamamoto, Harry Y.

RESUMO

A new ascorbate-induced chloroplast absorbance change which has the characteristics of a carotenoid shift is described. The absorbance change was light-dependent at pH 7 but not at pH 5. The difference spectra for the light and dark changes were similar, showing a large absorbance peak at 505 nanometers, smaller peaks near 468 and 437 nanometers, and a sharp valley around 483 nanometers. The absorbance change is assigned to violaxanthin de-epoxidation because various conditions affected the absorbance change and violaxanthin de-epoxidation similarly, and the difference spectrum resembled the spectrum of zeaxanthin minus violaxanthin in organic solvent.

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