Spectral studies on the denaturation of myoglobin

The protein from the sperm whale is significantly more stable than that from the horse and the apomyoglobins from sperm whale and horse undergo transitions at lower concentrations of denaturants than do their respective metmyoglOBins, and the data are again compatible with a one-step process.

Abstract

Absorption and fluorescence spectroscopy and optical rotation measurements have been used to follow the denaturation of sperm whale skeletal muscle and horse heart myoglobins by urea and guanidine hydrochloride. The spectral properties of the metmyoglobin forms of each of these proteins change concomitantly during denaturation, and the transitions are compatible with a one-step, cooperative denaturation process. The apomyoglobins from sperm whale and horse undergo transitions at lower concentrations of denaturants than do their respective metmyoglobins, and the data are again compatible with a one-step process. For both metmyoglobins and apomyoglobins, the protein from the sperm whale is significantly more stable than that from the horse. These results are discussed with respect to the chemical bases of the spectral properties, the location and relationship of the chromophores in the atomic model of the protein, and the forces which lead to structural stability.