title: Structural studies of staphylococcal protease. III. Binding of anions to the spin-labeled enzyme.
abstract: The staphylococcal protease was coupled at the active-site serine residue with a spin-labeled analog of diisopropyl fluorophosphonate and the interaction of competitive inhibitors such as chloride and acetate anions, as well as N-carbobenzoxy-L-glutamic acid (Z-L-Glu), was investigated by electron paramagnetic resonance spectroscopy. It was observed that the addition of chloride ions to the spin-labeled enzyme increased the freedom of motion of the spin label while the presence of acetate ions and Z-L-Glu resulted in an increase in the immobilization of the spin label. These results suggest that these ions bind to the active site region in different ways.
mesh_terms: D001665:Binding Sites; D004578:Electron Spin Resonance Spectroscopy; D010450:Endopeptidases; D007531:Isoflurophate; D011487:Protein Conformation; D012694:Serine; D013113:Spin Labels; D013211:Staphylococcus aureus / Q000201:enzymology*
chemical_list: D013113:Spin Labels; D007531:Isoflurophate; D012694:Serine; D010450:Endopeptidases