[Effect of temperature and pH on the environment of tryptophan residues in alpha-actinin]

Effects of temperature and pH on the structure of rabbit muscle alpha-actinin were studied by means of an intrinsic fluorescence method. Alkaline denaturation of alpha-actinin at 15 degrees C begins at pH above 9, while acidification of the solution does not cause unfolding of the protein structure, but results in protein aggregation. The maximal intensity of the isoelectric aggregation process is registered at pH 5. Thermal denaturation of alpha-actinin occurs within the temperature range from 45 degrees C to 65 degrees C. Protein has the second thermally induced transition in the region from 17 to 30 degrees C.