1kbi
From Proteopedia
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Crystallographic Study of the Recombinant Flavin-binding Domain of Baker's Yeast Flavocytochrome b2: Comparison with the Intact Wild-type Enzyme
Overview
Flavocytochrome b(2) catalyzes the oxidation of L-lactate to pyruvate and, the transfer of electrons to cytochrome c. The enzyme consists of a, flavin-binding domain, which includes the active site for lacate, oxidation, and a b(2)-cytochrome domain, required for efficient cytochrome, c reduction. To better understand the structure and function of intra- and, interprotein electron transfer, we have determined the crystal structure, of the independently expressed flavin-binding domain of flavocytochrome, b(2) to 2.50 A resolution and compared this with the structure of the, intact enzyme, redetermined at 2.30 A resolution, both structures being, from crystals cooled to 100 K. Whereas there is little overall difference, between these structures, we do observe significant local changes near the, interface region, some of which impact on amino acid side chains, such as, Arg289, that have been shown previously to have an important role in, catalysis. The disordered loop region found in flavocytochrome b(2) and, its close homologues remain unresolved in frozen crystals of the, flavin-binding domain, implying that the presence of the b(2)-cytochrome, domain is not responsible for this positional disorder. The flavin-binding, domain interacts poorly with cytochrome c, but we have introduced acidic, residues in the interdomain interface region with the aim of enhancing, cytochrome c binding. While the mutations L199E and K201E within the, flavin-binding domain resulted in unimpaired lactate dehydrogenase, activity, they failed to enhance electron-transfer rates with cytochrome, c. This is most likely due to the disordered loop region obscuring all or, part of the surface having the potential for productive interaction with, cytochrome c.
About this Structure
1KBI is a Single protein structure of sequence from Saccharomyces cerevisiae with PO4, HEM, FMN, PYR and MPD as ligands. Active as L-lactate dehydrogenase (cytochrome), with EC number 1.1.2.3 Full crystallographic information is available from OCA.
Reference
Crystallographic study of the recombinant flavin-binding domain of Baker's yeast flavocytochrome b(2): comparison with the intact wild-type enzyme., Cunane LM, Barton JD, Chen ZW, Welsh FE, Chapman SK, Reid GA, Mathews FS, Biochemistry. 2002 Apr 2;41(13):4264-72. PMID:11914072
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