Effective conversion of Chl a to Chl d catalyzed by papain

Abstract

In 1943, Chl d was first reported as a minor pigment in several red macroalgae. A novel cyanobacterium, Acaryochloris marina, was isolated from colonial ascidians, and A. marina was found to contain Chl d as the dominant chlorophyll. However, the biosynthesis pathway of Chl d has not been clarified yet. Chl d is thought to be synthesized from Chl a, like Chl b, while no experimental evidence is present. We came across the formation of Chl d from Chl a in organic solvents containing 10 % water in the presence of papain (EC 3.4.22.2) at room temperature in the dark; Chl d was not formed when papain was absent. The conversion of Chl a into Chl d in aqueous acetone in the presence of papain significantly increased, when incubated at 70^oC.