Fig. 3.

Cyclase activity measurements. (A) A fixed amount of P fraction (60 μg of protein) was incubated with various amounts of S fraction for 20 min. The maximal specific activity in this preparation was 112 pmol of protochlorophyllide per mg of protein for every 20-min period. (B) A fixed amount of S (230 μg of protein) was incubated with various amounts of P for 20 min. The maximal specific activity was 237 pmol of protochlorophyllide per mg of protein for every 20-min period. (C) The protochlorophyllide formation was followed by time. P (50 μg of protein) and S (240 μg of protein) were incubated under standard assay conditions except that samples were quenched at the various times indicated. The specific cyclase activity at 20 min was 393 pmol of protochlorophyllide per mg of protein for every 20-min period.