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EC 1.3.2.3 Details
show Brenda entryEC number
1.3.2.3
Accepted name
L-galactonolactone dehydrogenase
Reaction
L-galactono-1,4-lactone + 4 ferricytochrome c = L-dehydroascorbate + 4 ferrocytochrome c + 4 H+ (overall reaction);;(1a) L-galactono-1,4-lactone + 2 ferricytochrome c = L-ascorbate + 2 ferrocytochrome c + 2 H+;;(1b) L-ascorbate + 2 ferricytochrome c = L-dehydroascorbate + 2 ferrocytochrome c + 2 H+ (spontaneous)
Other name(s)
galactonolactone dehydrogenase,
L-galactono-γ-lactone dehydrogenase,
L-galactono-γ-lactone:ferricytochrome-c oxidoreductase,
GLDHase,
GLDase
Systematic name
L-galactono-1,4-lactone:ferricytochrome-c oxidoreductase
CAS registry number
9029-02-1
Comment
This enzyme catalyses the final step in the biosynthesis of L-ascorbic acid in higher plants and in nearly all higher animals with the exception of primates and some birds [5]. The enzyme is very specific for its substrate L-galactono-1,4-lactone as D-galactono-γ-lactone, D-gulono-γ-lactone, L-gulono-γ-lactone, D-erythronic-γ-lactone, D-xylonic-γ-lactone, L-mannono-γ-lactone, D-galactonate, D-glucuronate and D-gluconate are not substrates [5]. FAD, NAD+, NADP+ and O2 (cf. EC 1.3.3.12, L-galactonolactone oxidase) cannot act as electron acceptor [5].
History
created 1961, modified 2006
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1 Oxidoreductases
1.1 Acting on the CH-OH group of donors
1.3.1.23 created 1972, deleted 2005 1.3.1.50 created 1992, deleted 1999 1.3.1.55 created 1999, deleted 2004 1.3.2.1 created 1961, deleted 1964 1.3.2.2 created 1961, deleted 1964
