Formation of Chl d from Chl a catalyzed by papain

Abstract

Biosynthetic pathway of Chl d in Acaryochloris marina has not be chaified yet, although Chl d is thought to be systhesized from Chl a.
Recently we came across the formation of Chl d from Chl a in aqueous acetone with papain². Oxidative cleavage of a C=C double bond of a vinyl group in Chl a is necessary to yield Chl d. Chl a has many C=C bonds, so that it is too difficult to oxidize the sole C=C bond. In this study, we examined the reaction of Chl b and Phe a.
Similar reaction was observed in Chl b and Phe a with papain, although the reaction were very slow². Our finding will provide insight into the unsolved key question as to the biosynthetic pathway of Chl d via Chl a in A.marina.

1.Kobayashi et al., Photosynth. Res., 84, 201-207 (2005)
2.Koizumi et al., Sci. Tech. Advanced Materials, in press.