31P NMR spin-transfer in the phosphoglyceromutase reaction.
The rate of exchange of phosphoryl groups between 2- and 3-phosphoglycerate catalysed by (a) high concentrations (approximately equal to 5.0 mg protein ml-1) of rabbit muscle phosphoglyceromutase and (b) lysed human erythrocytes was measured using saturation and inversion transfer techniques with 31P-NMR spectroscopy. This is the first reported application of these techniques to a study of this particular enzymic reaction either in vitro or in situ in a cell cytosol. Selective irradiation of resonances was achieved by the DANTE pulse sequence which had not previously been used for spin-transfer studies. New equilibrium exchange theory was developed for the simplest model of a two-reactant enzyme-catalysed reaction and this was used to calculate turnover rates for the enzymes. There was a close similarity between the turnover rates calculated from the spin-transfer data obtained from the systems in vitro and in situ and those obtained by conventional enzymic assays, at low enzyme concentrations. This suggested an absence of any homogeneous enzyme-enzyme interactions which modify the kinetics at high protein concentrations either in lysates or in the system in vitro.
D000818:Animals; D004912:Erythrocytes / Q000201:enzymology; D005994:Glycerophosphates / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008433:Mathematics; D008956:Models, Chemical; D009132:Muscles / Q000201:enzymology; D010736:Phosphoglycerate Mutase / Q000097:blood / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D011817:Rabbits
D005994:Glycerophosphates; D010770:Phosphotransferases; D010736:Phosphoglycerate Mutase