title: Evaluation of 1-fluoro-2-nitro-4-trimethylammoniobenzene iodide, a protein-solubilizing reagent.
abstract: The new protein reagent 1-fluoro-2-nitro-4-trimethylammoniobenzene iodide reacts with model amino acids to give derivatives that are very stable to hydrolysis. In a dimethyl sulphoxide-water medium it reacts rapidly (3h) with bovine insulin, and substitution occurs quantitatively at the N-terminal amino groups and at the in-amino groups of lysine residues. Two of the four tyrosine residues react, and it is assumed that these are the exposed groups leaving the buried groups unattacked. Unlike 1-fluoro-2,4-dinitrobenzene and related reagents, it imparts hydrophilic properties to the protein derivative, thus facilitating structural and other studies on the derivative. Circular-dichroism spectra of the modified insulin suggest that no conformational changes have occurred during reaction. These spectra also reveal the presence of an extrinsic Cotton effect at 410nm.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000814:Aniline Compounds; D001555:Benzene Derivatives / Q000138:chemical synthesis; D002854:Chromatography, Paper; D002942:Circular Dichroism; D005998:Glycine; D006868:Hydrolysis; D007202:Indicators and Reagents; D007328:Insulin / Q000032:analysis; D007700:Kinetics; D011506:Proteins / Q000032:analysis*; D012995:Solubility
chemical_list: D000596:Amino Acids; D000814:Aniline Compounds; D001555:Benzene Derivatives; D007202:Indicators and Reagents; D007328:Insulin; D011506:Proteins; D005998:Glycine