title: Nuclear magnetic relaxation study on the interaction of glycyl-L-tyrosine with manganese-carboxypeptidase A in solution.
abstract: The spin-lattice and spin-spin relaxation rates were measured of the Gly C alpha and Tyr aryl protons of glycyl-L-tyrosine (Gly-Tyr) bound to manganese(II)-substituted carboxypeptidase A (MnCPA) in aqueous solution. The temperature and frequency dependences of the relaxation rates were analyzed using the Solomon-Bloembergen-Morgan equations. The binding modes of MnCPA with Gly-Tyr in solution are different from that of ZnCPA in crystals. 1. Mn(II)-coordinated water of MnCPA is not excluded by the binding of Gly-Tyr substrate molecules. 2. The Gly carbonyl group does not coordinate tightly to the metal ion of MnCPA. The Gly C alpha protons of Gly-Tyr in the productive binding site are appreciably mobile. 3. A non-productive loose binding of another Gly-Tyr molecule is suggested by simulation of the temperature and frequency dependences of the proton relaxation rates.
mesh_terms: D001665:Binding Sites; D002268:Carboxypeptidases; D004151:Dipeptides; D005998:Glycine; D009682:Magnetic Resonance Spectroscopy; D008345:Manganese; D008433:Mathematics; D011485:Protein Binding; D011487:Protein Conformation; D013816:Thermodynamics; D014443:Tyrosine
chemical_list: D004151:Dipeptides; D014443:Tyrosine; D008345:Manganese; D002268:Carboxypeptidases; D005998:Glycine