2f32
From Proteopedia
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Xray crystal structure of lysozyme mutant L20/R63A liganded to ethylguanidinium
Overview
The binding of guanidinium ion has been shown to promote a large-scale translation of a tandemly duplicated helix in an engineered mutant of T4 lysozyme. The guanidinium ion acts as a surrogate for the guanidino group of an arginine side chain. Here we determine whether methyl- and ethylguanidinium provide better mimics. The results show that addition of the hydrophobic moieties to the ligand enhances the binding affinity concomitant with reduction in ligand solubility. Crystallographic analysis confirms that binding of the alternative ligands to the engineered site still drives the large-scale conformational change. Thermal analysis and NMR data show, in comparison to guanidinium, an increase in protein stability and in ligand affinity. This is presumably due to the successive increase in hydrophobicity in going from guanidinium to ethylguanidinium. A fluorescence-based optical method was developed to sense the ligand-triggered helix translation in solution. The results are a first step in the de novo design of a molecular switch that is not related to the normal function of the protein.
About this Structure
2F32 is a Single protein structure of sequence from Bacteriophage t4 with and as ligands. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
Guanidinium derivatives bind preferentially and trigger long-distance conformational changes in an engineered T4 lysozyme., Yousef MS, Bischoff N, Dyer CM, Baase WA, Matthews BW, Protein Sci. 2006 Apr;15(4):853-61. PMID:16600969
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