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PDBsum entry 3e2n
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Oxidoreductase
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PDB id
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3e2n
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References listed in PDB file
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Key reference
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Title
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Engineering ascorbate peroxidase activity into cytochrome c peroxidase.
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Authors
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Y.T.Meharenna,
P.Oertel,
B.Bhaskar,
T.L.Poulos.
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Ref.
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Biochemistry, 2008,
47,
10324-10332.
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PubMed id
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Abstract
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Cytochrome c peroxidase (CCP) and ascorbate peroxidase (APX) have very similar
structures, and yet neither CCP nor APX exhibits each other's activities with
respect to reducing substrates. APX has a unique substrate binding site near the
heme propionates where ascorbate H-bonds with a surface Arg and one heme
propionate (Sharp et al. (2003) Nat. Struct. Biol. 10, 303-307). The
corresponding region in CCP has a much longer surface loop, and the critical Arg
residue that is required for ascorbate binding in APX is Asn in CCP. In order to
convert CCP into an APX, the ascorbate-binding loop and critical arginine were
engineered into CCP to give the CCP2APX mutant. The mutant crystal structure
shows that the engineered site is nearly identical to that found in APX. While
wild-type CCP shows no APX activity, CCP2APX catalyzes the peroxidation of
ascorbate at a rate of approximately 12 min (-1), indicating that the engineered
ascorbate-binding loop can bind ascorbate.
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