ABSTRACT
Denaturation of Bacillus thuringiensis CryIIIA delta-endotoxin--an insecticidal protein, active against Coleoptera larvae--in concentrated guanidine hydrochloride solutions was pursued by fluorescence and circular dichroism spectroscopy and limited proteolysis. It was found that the protein consists of two fragments that differ by their stability to denaturation by guanidine hydrochloride at pH 3. The less stable fragment corresponds to the N-terminal alpha-helical domain limited by Leu-279; the more stable one starts with Ile-280, contains about 330 amino acid residues, and corresponds to the molecule C-terminal moiety that consist of its two beta-structural domains forming a superdomain.
Subject(s)
Bacillus thuringiensis/chemistry , Bacterial Proteins/chemistry , Bacterial Toxins , Endotoxins/chemistry , Guanidines , Pepsin A/metabolism , Amino Acid Sequence , Bacillus thuringiensis Toxins , Circular Dichroism , Guanidine , Hemolysin Proteins , Hydrogen-Ion Concentration , Molecular Sequence Data , Peptide Fragments/chemistry , Protein Denaturation , Protein Structure, Secondary , Spectrometry, FluorescenceABSTRACT
Possible applications of the Coomassie brilliant blue G-250 dye method for protein assay are reviewed. The physico-chemical and optical properties of the dye are considered in detail. The data on the protein-binding mechanism are generalized. Modifications of the Coomassie blue G-250 quantitative protein assays are critically considered. The applications of the method in medicine, biochemistry and biotechnology are discussed.
