PRIMARY REACTIONS IN BACTERIAL PHOTOSYNTHESIS—II. THE QUANTUM REQUIREMENT FOR BACTERIOCHLOROPHYLL CONVERSION IN THE CHROMATOPHORE

Abstract

Summary Reversible light‐induced alteration of a special component of bacteriochlorophyll (BChl,) is observed in bacterial chromatophores. The alteration involves bleaching of the long‐wave absorption band at 870–890 mp and a blue shift of the band at 800 mp. Assuming that the altered BChl, molecule loses all of its long‐wave absorption, and that the extinction coefficient of this band is equal to that of the corresponding band in the major component of BChl, a quantum requirement could be computed for the light‐induced change. It was found with most preparations that two to four quanta suffice for the alteration of one BChl, molecule, even in dried chromatophores at 1° K. This result is taken as supporting evidence for the importance of light‐induced BChl, conversion in photosynthesis. It also shows that BChl, is effective as an energy sink in the chromatophore.

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Identifiers

DOI

10.1111/j.1751-1097.1962.tb08106.x

Journal

Photochemistry and Photobiology

Year

1962