Open AccessSubstrate Specificity of Chlorophyll(ide) b Reductase in Etioplasts of Barley ( Hordeurn Vulgare L.)
Author(s) -
Scheumann Verena,
Ito Hisashi,
Tanaka Ayumi,
Schoch Siegrid,
Rüdiger Wolfhart
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0163r.x
Subject(s) - pheophorbide a , chlorophyll , chemistry , substrate (aquarium) , biochemistry , reductase , enzyme , protochlorophyllide , biology , organic chemistry , biosynthesis , ecology
Enzyme activity of chlorophyll(ide) b reductase is present in etioplasts. Recently the conversion of chlorophyllide b to chlorophyll a via 7 1 ‐hydroxychlorophyll a was demonstrated in barley etioplasts. We used zinc pheophorbide b for a detailed investigation of the reduction of the 7‐formyl group to the 7 l ‐hydroxy compound in intact barley etioplasts. The reaction proceeded likewise before esterification and after esterification with phytyl diphosphate. The metal‐free pheophorbide b , that is not accepted by chlorophyll synthase for esterification, is reduced to 7 1 ‐hydroxypheophorbide a to a small extent. The zinc (13 2 S )‐pheophorbide b is at least equally well accepted for reduction as the epimer with the 13 2 R configuration of natural chlorophyll b. The reaction requires NADPH or NADH, although the latter is less effective. ATP is not required for the first step to the 7 1 ‐hydroxy compound. The significance of chlorophyll b reduction for acclimation from shade to sun leaves and for chlorophyll degradation is discussed.