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PDBsum entry 4ue3
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Oxidoreductase
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PDB id
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4ue3
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References listed in PDB file
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Key reference
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Title
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Mechanism of hydrogen activation by [nife] hydrogenases.
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Authors
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R.M.Evans,
E.J.Brooke,
S.A.Wehlin,
E.Nomerotskaia,
F.Sargent,
S.B.Carr,
S.E.Phillips,
F.A.Armstrong.
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Ref.
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Nat Chem Biol, 2016,
12,
46-50.
[DOI no: ]
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PubMed id
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Abstract
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The active site of [NiFe] hydrogenases contains a strictly conserved arginine
that suspends a guanidine nitrogen atom <4.5 Å above the nickel and iron
atoms. The guanidine headgroup interacts with the side chains of two conserved
aspartic acid residues to complete an outer-shell canopy that has thus far
proved intractable to investigation by site-directed mutagenesis. Using
hydrogenase-1 from Escherichia coli, the strictly conserved residues R509 and
D574 have been replaced by lysine (R509K) and asparagine (D574N) and the highly
conserved D118 has been replaced by alanine (D118A) or asparagine (D118N/D574N).
Each enzyme variant is stable, and their [(RS)2Niμ(SR)2Fe(CO)(CN)2] inner
coordination shells are virtually unchanged. The R509K variant had >100-fold
lower activity than native enzyme. Conversely, the variants D574N, D118A and
D118N/D574N, in which the position of the guanidine headgroup is retained,
showed 83%, 26% and 20% activity, respectively. The special kinetic requirement
for R509 implicates the suspended guanidine group as the general base in H2
activation by [NiFe] hydrogenases.
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