title: FmRα analysis: Rapid and direct estimation of relaxation and kinetic parameters from dynamic nuclear polarization time courses.
abstract: OBJECTIVE
  To introduce a direct method for estimating relaxation and kinetic parameter values from rapid dissolution dynamic nuclear polarization (RD-DNP) NMR time courses.
  
  
  METHODS
  The analysis relied on a kinetic model that is often used to analyze data in these studies-a unidirectional (bio)chemical reaction with rate constant k1 , coupled to longitudinal relaxation of the magnetization of substrate and product that is characterized by the time constant T1 . The latter value was estimated from the width of the product curve (peak) at the height α relative to the maximum height. We showed α ∼ 0.8 under most conditions, so we measured the interval between the falling and rising parts of the curve at the relative height 0.8. We called this the "fall-minus-rise time at height α," or FmRα , and found that FmR0.8 ∼ T1 . The ratio β = (product signal/substrate signal) when the product is maximal was shown to be equal to k1 T1 . Therefore, k1 = β/FmR0.8 .
  
  
  RESULTS
  FmRα analysis was demonstrated with (13) C NMR RD-DNP data recorded from hemolysates and from previously published data.
  
  
  CONCLUSIONS
  FmRα analysis enables immediate estimates of kinetic and relaxation parameters from (13) C NMR RD-DNP data. The values can be used as initial estimates in more extensive computer-based data-regression analysis.
authors.affiliation: Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore.|Currently at: Groupe de RMN Biomédicale, Laboratoire de Synthèse et Physico-Chimie de Molécules d'Intérêt Biologique, UMR CNRS 5068, Université de Toulouse, 118 route de Narbonne, 31062 Toulouse cedex, France.
authors.forename: Guilhem
authors.initials: G
authors.lastname: Pagès
authors.affiliation: School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Philip W
authors.initials: PW
authors.lastname: Kuchel
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D002247:Carbon Isotopes; D005650:Fumarates / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D019344:Lactic Acid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008293:Malates / Q000378:metabolism; D051379:Mice; D008956:Models, Chemical; D015233:Models, Statistical; D019289:Pyruvic Acid / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D005650:Fumarates; D008293:Malates; D019344:Lactic Acid; C030298:malic acid; D019289:Pyruvic Acid; C032005:fumaric acid; D005978:Glutathione; D001205:Ascorbic Acid
keywords: data fitting; erythrocyte; fall minus rise method; hyperpolarization; lactate dehydrogenase (LDH); simple kinetic model