DYE REDUCTION BY ILLUMINATED CHLOROPLAST FRAGMENTS

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Abstract
The rate of reduction of dilute solns. of indophenol dyes, approx. 1-3 x 10-5 M, can be used as a measure of the photochemical activity of micro quantities of chloroplast material. The initial rate of dye reduction can be measured within a period of 1 min. with a precision of [plus and minus] 2% using a photometric method and continuous recorder. Less rapid and more scattered results are obtained when the time required for complete decolorization (estimated visually) is used. Reduction of 2,6-dichlorobenzenone-indo-3'' -chlorophenol is fastest at pH 5.9. The temp. coeff. for reduction of this dye is approx. 1.7 for the temp. range 5-35[degree]C. Precipitation, adsorption, and differential centrifugation of preparations of chloroplasts disintegrated by supersonic vibrations failed to yield any fractions possessing noteworthy enhancements of photochemical activity.