A Short Lived Intermediate in the Photoconversion of Protochlorophyllide to Chlorophyllide a

The transient absorption change for the photoreduction of protochlorophyllide(PChlide) was studied with a solution of extracted PChlide holochromeand with etiolated leaves. The following results were obtained:(1) A short-lived intermediate with an absorption maximum at690 nm was found before formation of chlorophyllide a (Chlide).(2) The intermediate appeared instantly at the onset of theactinic laser, and it decayed very fast with a rate constantof 3.4 x 10⁵ sec^–1. (3) This decay constant for the intermediateagreed well with the rate constants for Chlide formation, 3.1x 10⁵ sec^–1 for the extract and 4.6 x 10⁵ sec^–1for the etiolated leaves. ¹Present address: Department of Botany, Faculty of Science,Kyoto University, Kitashirakawa, Kyoto 606, Japan. (Received September 24, 1980; Accepted December 6, 1980)