Friesen-Waldner, L.J., et al., Direct enzyme-substrate affinity determination by real-time hyperpolarized (13)C-MRS. Chem Commun (Camb), 2014. 50(89): p. 13801-4.
http://www.ncbi.nlm.nih.gov/pubmed/25253534
A specialized kinetic analysis of real-time hyperpolarized [1,1,2,2-D4, 1-(13)C]choline (13)C-magnetic resonance spectroscopy enabled the determination of initial rates of metabolic enzyme activity (choline oxidase), enzyme-substrate affinity (Km), and inhibition. In a clinical MRI scanner, metabolite levels lower than 16 muM were detected at a temporal resolution of 1 s.