Thermolysin-inhibitor complexes examined by 31P and 113Cd NMR spectroscopy.
Complexes between phosphoramidon (N-(alpha-rhamnopyranosyloxyhydroxyphosphinyl)-L-leucyl-L-tryptoph an) and zinc thermolysin and between phosphoramidon or N-phosphoryl-L-leucineamide and 113Cd-substituted thermolysin have been examined by 31P and 113Cd NMR spectroscopy. 113Cd resonances are observed at 168 and 152 ppm for the phosphoramidon and N-phosphoryl-L-leucineamide complexes, respectively. There are large but different chemical shift anisotropy contributions to the 113Cd line widths for the two complexes, which reflect the known structural differences for the zinc-enzyme complexes. 113Cd-31P spin-spin coupling is also seen and differs for the two cadmium complexes, being larger, 28 Hz, for the bidentate N-phosphoryl-L-leucineamide ligand than for the monodentate phosphoramidon, 16 Hz. Large changes in chemical shift, 7.5-10.9 ppm, are seen for the 31P resonances of the inhibitors upon binding to the enzyme reflecting direct phosphoryl-metal ligation. Chemical shift anisotropy is the dominant relaxation mechanism for the 31P nuclei at 9.4 T, while the dipole-dipole contribution seems to be unaffected by a change of solvent from H2O to D2O.
Gettins
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Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
D002104:Cadmium; D006020:Glycopeptides / Q000378:metabolism*; D007554:Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010758:Phosphorus; D011485:Protein Binding; D011487:Protein Conformation; D013820:Thermolysin / Q000037:antagonists & inhibitors*; D014961:X-Ray Diffraction
D006020:Glycopeptides; D007554:Isotopes; D002104:Cadmium; D010758:Phosphorus; D013820:Thermolysin; C008890:phosphoramidon