Partial characterization of suberitine, the neurotoxic protein purified from Suberites domuncula

Abstract

1. 1. The protein (mol. wt 28.000) consists of four subunits, which are not equivalent as regards the chemical composition, although all of them lack free terminal amino groups. 2. 2. The single subunits also possess different conformations since both photosensitized oxidation studies and acrylamide-quenching experiments of the protein fluorescence emission show that the three tryptophyl residues have a different accessibility to the aqueous solvent. 3. 3. Circular dichroism and fluorescence polarization studies suggest that suberitine has a remarkable tight three-dimensional organization: e.g., exposure of suberitine to 6 M urea for several hours is necessary to obtain a general unfolding of the protein molecule.