Changes in the Properties of Protochlorophyllide Reductase during Early Greening of Etiolated Squash Cotyledons

A photoconvertible complex of protochlorophyllide (Pchld) and protein, called Pchld holochrome has been isolated from various etiolated seedlings with (1–6) or without (7–9) the aid of detergents. The molecular size of the Pchld holochrome has been extensively studied, but is still controversial (10) ranging widely from 600,000 to 63,000. Changes in size, and spectroscopic and physicochemical properties have also been reported. Illumination of the isolated Pchld holochrome induces a decrease of its apparent molecular size, probably indicating partial dissociation of the components of the Pchld holochrome (11–13).