title: Phosphorescence evidence for the role of solvent--protein interactions in the energetics of conformational flexibility of liver alcohol dehydrogenase.
abstract: When tryptophyl side chains are hidden within relatively inflexible domains of globular proteins, the lifetime of the phosphorescence from these residues provides a measure of the local conformational flexibility. The phosphorescence decay from the tryptophan buried at the base of the nucleotide-binding domain in liver alcohol dehydrogenase (alcohol:NAD+ oxidoreductase, EC 1.1.1.1) was monitored between 1 and 40 degrees C to determine the energetics associated with the rate of local unfolding. The slow rate at which this process takes place is found to result from a high entropic barrier rather than from the disruption of strong intramolecular interactions. This observation along with the response of the system to solvent perturbations points to the significance of solvent-protein interactions in determining conformational flexibility.
mesh_terms: D000429:Alcohol Oxidoreductases; D000818:Animals; D006736:Horses; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008163:Luminescent Measurements; D011487:Protein Conformation; D012997:Solvents; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D012997:Solvents; D000429:Alcohol Oxidoreductases