1hyu
From Proteopedia
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CRYSTAL STRUCTURE OF INTACT AHPF
Overview
AhpF, a homodimer of 57 kDa subunits, is a flavoenzyme which catalyzes the, NADH-dependent reduction of redox-active disulfide bonds in the peroxidase, AhpC, a member of the recently identified peroxiredoxin class of, antioxidant enzymes. The structure of AhpF from Salmonella typhimurium at, 2.0 A resolution, determined using multiwavelength anomalous dispersion, shows that the C-terminal portion of AhpF (residues 210-521) is, structurally like Escherichia coli thioredoxin reductase. In addition, AhpF has an N-terminal domain (residues 1-196) formed from two contiguous, thioredoxin folds, but containing just a single redox-active disulfide, (Cys129-Cys132). A flexible linker (residues 197-209) connects the, domains, consistent with experiments showing that the N-terminal domain, acts as an appended substrate, first being reduced by the C-terminal, portion of AhpF, and subsequently reducing AhpC. Modeling studies imply, that an intrasubunit electron transfer accounts for the reduction of the, N-terminal domain in dimeric AhpF. Furthermore, comparing the N-terminal, domain with protein disulfide oxidoreductase from Pyrococcus furiosis, we, describe a new class of protein disulfide oxidoreductases based on a novel, mirror-image active site arrangement, with a distinct carboxylate (Glu86), being functionally equivalent to the key acid (Asp26) of E. coli, thioredoxin. A final fortuitous result is that the N-terminal redox center, is reduced and provides a high-resolution view of the thiol-thiolate, hydrogen bond that has been predicted to stabilize the attacking thiolate, in thioredoxin-like proteins.
About this Structure
1HYU is a Single protein structure of sequence from Salmonella typhimurium with SO4, CL and FAD as ligands. Full crystallographic information is available from OCA.
Reference
Structure of intact AhpF reveals a mirrored thioredoxin-like active site and implies large domain rotations during catalysis., Wood ZA, Poole LB, Karplus PA, Biochemistry. 2001 Apr 3;40(13):3900-11. PMID:11300769
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