EC - Chlorophyll(ide) b reductase

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IntEnz Enzyme Nomenclature


Accepted name:
chlorophyll(ide) b reductase
Other names:
chlorophyll b reductase
Chl b reductase
Systematic name:
71-hydroxychlorophyllide-a:NAD(P)+ oxidoreductase



This enzyme carries out the first step in the conversion of chlorophyll b to chlorophyll a. It is involved in chlorophyll degradation, which occurs during leaf senescence [3,4] and it also forms part of the chlorophyll cycle, which interconverts chlorophyll a and b in response to changing light conditions [5,6]. While both chlorophyll a and chlorophyll b are found in higher plants, only breakdown products derived from chlorophyll a are found in the end products, i.e. non-fluorescent chlorophyll catabolites (NCCs). The transition from chlorophyll b, which contains a formyl group on C7, to chlorophyll a, which contains a methyl group on C7, proceeds through the intermediate 71-hydroxychlorophyll [1]. Another enzyme, which requires ferredoxin but has not been characterized fully, is required to complete the conversion [3].

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00060
Structural data: CSA , EC2PDB
Gene Ontology: GO:0034256


  1. Scheumann, V., Ito, H., Tanaka, A., Schoch, S. and Rüdiger, W.
    Substrate specificity of chlorophyll(ide) b reductase in etioplasts of barley (Hordeum vulgare L.).
    Eur. J. Biochem. 242: 163-170 (1996). [PMID: 8954166]
  2. Scheumann, V., Schoch, S. and Rüdiger, W.
    Chlorophyll a formation in the chlorophyll b reductase reaction requires reduced ferredoxin.
    J. Biol. Chem. 273: 35102-35108 (1998). [PMID: 9857045]
  3. Scheumann, V., Schoch, S. and Rüdiger, W.
    Chlorophyll b reduction during senescence of barley seedlings
    Planta 209: 364-370 (1999). [PMID: 10502104]
  4. Hörtensteiner, S.
    Chlorophyll degradation during senescence.
    Annu. Rev. Plant Biol. 57: 55-77 (2006). [PMID: 16669755]
  5. Ito, H., Ohtsuka, T. and Tanaka, A.
    Conversion of chlorophyll b to chlorophyll a via 7-hydroxymethyl chlorophyll.
    J. Biol. Chem. 271: 1475-1479 (1996). [PMID: 8576141]
  6. Rüdiger, W.
    Biosynthesis of chlorophyll b and the chlorophyll cycle.
    Photosyn. Res. 74: 187-193 (2002). [PMID: 16228557]

[EC created 2007]