Abstract
The reduction of chlorophyllide b and its analogue zinc pheophorbide b in etioplasts of barley (Hordeum vulgare L.) was investigated in detail. In intact etioplasts, the reduction proceeds to chlorophyllide a and zinc pheophorbide a or, if incubated together with phytyldiphosphate, to chlorophyll a and zinc pheophytin a, respectively. In lysed etioplasts supplied with NADPH, the reduction stops at the intermediate step of 7(1)-OH-chlorophyll(ide) and Zn-7(1)-OH-pheophorbide or Zn-7(1)-OH-pheophytin. However, the final reduction is achieved when reduced ferredoxin is added to the lysed etioplasts, suggesting that ferredoxin is the natural cofactor for reduction of chlorophyll b to chlorophyll a. The reduction to chlorophyll a requires ATP in intact etioplasts but not in lysed etioplasts when reduced ferredoxin is supplied. The role of ATP and the significance of two cofactors for the two steps of reduction are discussed.
Highlights
Chlorophylls (Chls)1 are abundant pigments of photosynthesis in marine, aquatic, and terrestrial environments
In lysed etioplasts supplied with NADPH, the reduction stops at the intermediate step of 71-OHchlorophyll(ide) and Zn-71-OH-pheophorbide or Zn-71OH-pheophytin
The only difference in these chlorophyll structures is located at C-7; the substituent is a formyl group in Chl b but a methyl group in Chl a
Summary
Chlorophyll; Chlide, chlorophyllide; Pheide, pheophorbide; Phe, pheophythin; HPLC, high pressure liquid chromatography; POP, diphosphate. The Tanaka group detected the in vitro reduction of the formyl group to the methyl group of Chl derivatives when they investigated the esterification of chlorophyllide (Chlide) b with etioplasts from cucumber and barley (16 –18). In cooperation with TanakaЈs group, we showed that the first step, reduction of ZnPheide b to Zn-71-OH-Phe(ide) a, proceeds before or after esterification in purified, broken etioplasts of barley [22]. This step required NADPH or NADH but no ATP. We describe the second step, the formation of Chl a and ZnPhe(ide) a, in more detail; we compare this reduction in both intact and broken etioplasts and describe the effect of ATP. The comparison led to the discovery that the second step of reduction requires reduced ferredoxin
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
