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Quantification of rate constants for successive enzymatic reactions with DNP hyperpolarized MR
Author(s) -
AlloucheAr Hyla,
Hovav Yonatan,
FriesenWaldner Lanette,
Sosna Jacob,
Moshe Gomori J.,
Vega Shimon,
KatzBrull Rachel
Publication year - 2014
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3102
Subject(s) - betaine , chemistry , choline oxidase , choline , choline chloride , reaction rate constant , reaction rate , kinetics , analytical chemistry (journal) , nuclear magnetic resonance , enzyme , chromatography , organic chemistry , biochemistry , physics , quantum mechanics , acetylcholinesterase , catalysis
A kinetic model is provided to obtain reaction rate constants in successive enzymatic reactions that are monitored using NMR spectroscopy and hyperpolarized substrates. The model was applied for simulation and analysis of the successive oxidation of choline to betaine aldehyde, and further to betaine, by the enzyme choline oxidase. This enzymatic reaction was investigated under two different sets of conditions: two different choline molecular probes were used, [1,1,2,2‐D 4 , 1‐ 13 C]choline chloride and [1,1,2,2‐D 4 , 2‐ 13 C]choline chloride, in different MR systems (clinical scanner and high‐resolution spectrometer), as well as in different reactors and reaction volumes (4.8 and 0.7 mL). The kinetic analysis according to the model yielded similar results in both set‐ups, supporting the robustness of the model. This was achieved despite the complex and negating influences of reaction kinetics and polarization decay, and in the presence of uncontrolled mixing characteristics, which may introduce uncertainties in both effective timing and effective pulses. The ability to quantify rate constants using hyperpolarized MR in the first seconds of consecutive enzyme activity is important for further development of the utilization of dynamic nuclear polarization‐MR for biological determinations. Copyright © 2014 John Wiley & Sons, Ltd.