Rotational freedom of tryptophan residues in proteins and peptides.

摘要: We studied the rotational motions of tryptophan residues in proteins and peptides by measurement steady-state fluorescence anisotropies under conditions oxygen quenching. By quenching we can shorten lifetime thereby decrease average time for diffusion prior to emission. This method allowed correlation times ranging from 0.03 50 ns, when unquenched fuorescence lifetimes are near 4 ns. A wide range were investigated with molecular weights 200 80 000. Many chosen substances possessed a single residue minimize uncertainties arising heterogeneous population fluorophores. In addition, also number multi-tryptophan proteins. Proteins at various temperatures, self-association, presence denaturants. variety found. As examples note that myelin basic protein was highly mobile relative overall rotation whereas human serum albumin, RNase T1, aldolase, horse liver alcohol dehydrogenase found be immobile matrix. These results indicate one cannot generalize about extent segmental mobility physical property is variable between probably different regions same protein.