1gmk
From Proteopedia
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GRAMICIDIN/KSCN COMPLEX
Overview
The hydrophobic channel-forming polypeptide gramicidin adopts a, left-handed antiparallel double helix conformation with 6.4 residues per, turn when in complex with monovalent cation salts in a methanol, environment. The crystal structure of the gramicidin/potassium thiocyanate, complex (a = 32.06 A, b = 51.80 A, and c = 31.04 A; space group, P2(1)2(1)2(1)) has been solved to 2.5 A with an R-factor of 0.193. In the, structure, binding sites for the cations are formed by the polypeptide, backbone carbonyl groups tilting away from the helix axis toward the ions, located in the central lumen. The polypeptide backbone conformations and, the side-chain orientations in this potassium complex are significantly, different from those in the previously solved gramicidin/caesium chloride, crystal complex, due to the requirements for interactions with the smaller, sized potassium cation. The locations and numbers of potassium binding, sites also differ considerably from the locations and numbers of caesium, binding sites in the other structure. Combining information from all the, cation binding sites in the two gramicidin/ion complexes produces, different views of the three-dimensional structures of a cation as it is, transported along a transmembrane pore, and provides an experimental, structural basis for modeling the dynamics of peptide-ion binding and ion, transport.
About this Structure
1GMK is a Protein complex structure of sequences from Brevibacillus brevis with K, SCN, FOR and MOH as ligands. Structure known Active Sites: K2 and K4. Full crystallographic information is available from OCA.
Reference
Crystal structure of the gramicidin/potassium thiocyanate complex., Doyle DA, Wallace BA, J Mol Biol. 1997 Mar 14;266(5):963-77. PMID:9086274
Page seeded by OCA on Mon Nov 5 16:15:10 2007
