In collaboration with the group of E. Haas we have investigated the effect of a small """"""""inert"""""""" cosolute, trimethylamine oxide, on the conformational isomerization of an enzyme, adenylate kinase, that is known to undergo significant conformational changes during its catalytic cycle. Binding of substrate nucleotides (AMP, ADP, ATP, or analogs thereof) is accompanied by compaction resulting from the closure of clefts containing ligand binding sites. Conformational changes are being characterized via time-dependent fluorescence resonance energy transfer (FRET) between donor and acceptor fluorophores placed at selected locations along the peptide chain through site-specific mutagenesis. Analysis of the results obtained to date indicate that sufficient concentrations of TMAO stabilize compact or """"""""closed"""""""" conformations relative to less compact or """"""""open"""""""" conformations, leading to a substantial increase in the affinity of the enzyme for ligands. A report of this work was recently published.

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Hoppe, Travis; Minton, Allen P (2015) An equilibrium model for the combined effect of macromolecular crowding and surface adsorption on the formation of linear protein fibrils. Biophys J 108:957-66
Beg, Ilyas; Minton, Allen P; Hassan, Imtaiyaz et al. (2015) Thermal Stabilization of Proteins by Mono- and Oligosaccharides: Measurement and Analysis in the Context of an Excluded Volume Model. Biochemistry 54:3594-603
Wu, Di; Minton, Allen P (2013) Compensating effects of urea and trimethylamine-N-oxide on the heteroassociation of ?-chymotrypsin and soybean trypsin inhibitor. J Phys Chem B 117:3554-9
Minton, Allen P (2013) Quantitative assessment of the relative contributions of steric repulsion and chemical interactions to macromolecular crowding. Biopolymers 99:239-44
Fernández, Cristina; Minton, Allen P (2011) Effect of nonadditive repulsive intermolecular interactions on the light scattering of concentrated protein-osmolyte mixtures. J Phys Chem B 115:1289-93
Nagarajan, Sureshbabu; Amir, Dan; Grupi, Asaf et al. (2011) Modulation of functionally significant conformational equilibria in adenylate kinase by high concentrations of trimethylamine oxide attributed to volume exclusion. Biophys J 100:2991-9
Fodeke, Adedayo A; Minton, Allen P (2010) Quantitative characterization of polymer-polymer, protein-protein, and polymer-protein interaction via tracer sedimentation equilibrium. J Phys Chem B 114:10876-80
Tsao, Douglas; Minton, Allen P; Dokholyan, Nikolay V (2010) A didactic model of macromolecular crowding effects on protein folding. PLoS One 5:e11936
Jiao, Ming; Li, Hong-Tao; Chen, Jie et al. (2010) Attractive protein-polymer interactions markedly alter the effect of macromolecular crowding on protein association equilibria. Biophys J 99:914-23
Zhou, Huan-Xiang; Rivas, German; Minton, Allen P (2008) Macromolecular crowding and confinement: biochemical, biophysical, and potential physiological consequences. Annu Rev Biophys 37:375-97