1nvo
From Proteopedia
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Solution structure of a four-helix bundle model, apo-DF1
Overview
De novo protein design provides an attractive approach to critically test, the features that are required for metalloprotein structure and function., Previously we designed and crystallographically characterized an idealized, dimeric model for the four-helix bundle class of diiron and dimanganese, proteins [Dueferri 1 (DF1)]. Although the protein bound metal ions in the, expected manner, access to its active site was blocked by large bulky, hydrophobic residues. Subsequently, a substrate-access channel was, introduced proximal to the metal-binding center, resulting in a protein, with properties more closely resembling those of natural enzymes. Here we, delineate the energetic and structural consequences associated with the, introduction of these binding sites. To determine the extent to which the, binding site was preorganized in the absence of metal ions, the apo, structure of DF1 in solution was solved by NMR and compared with the, crystal structure of the di-Zn(II) derivative. The overall fold of the apo, protein was highly similar to that of the di-Zn(II) derivative, although, there was a rotation of one of the helices. We also examined the, thermodynamic consequences associated with building a small, molecule-binding site within the protein. The protein exists in an, equilibrium between folded dimers and unfolded monomers. DF1 is a highly, stable protein (K(diss) = 0.001 fM), but the dissociation constant, increases to 0.6 nM (deltadeltaG = 5.4 kcalmol monomer) as the active-site, cavity is increased to accommodate small molecules.
About this Structure
1NVO is a Protein complex structure of sequences from [1] with ACE and NH2 as ligands. Full crystallographic information is available from OCA.
Reference
Preorganization of molecular binding sites in designed diiron proteins., Maglio O, Nastri F, Pavone V, Lombardi A, DeGrado WF, Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):3772-7. Epub 2003 Mar 24. PMID:12655072
Page seeded by OCA on Sat Nov 24 23:53:13 2007
