Difference between Extra‐ and Intracellular T1 Values of Carboxylic Acids Affects the Quantitative Analysis of Cellular Kinetics by Hyperpolarized NMR. Issue 43 (26th September 2016)

• Record Type: Journal Article
• Authors: Karlsson, Magnus; Jensen, Pernille Rose; Ardenkjær‐Larsen, Jan Henrik; Lerche, Mathilde H.
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 43(2016)
• Page Start: 13567
• Page End: 13570
• Publication Date: 2016-09-26
• Subjects: carboxylic acids -- dissolution DNP -- hyperpolarization -- longitudinal relaxation -- NMR spectroscopy; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201607535
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Incomplete knowledge of the longitudinal relaxation time constant ( T 1 ) leads to incorrect assumptions in quantitative kinetic models of cellular systems, studied by hyperpolarized real‐time NMR. Using an assay that measures the intracellular signal of small carboxylic acids in living cells, the intracellular T 1 of the carboxylic acid moiety of acetate, keto‐isocaproate, pyruvate, and butyrate was determined. The intracellular T 1 is shown to be up to four‐fold shorter than the extracellular T 1 . Such a large difference in T 1 values between the inside and the outside of the cell has significant influence on the quantification of intracellular metabolic activity. It is expected that the significantly shorter T 1 value of the carboxylic moieties inside cells is a result of macromolecular crowding. An artificial cytosol has been prepared and applied to predict the T 1 of other carboxylic acids. We demonstrate the value of this prediction tool. Abstract : Time to relax : pH capture of small carboxylic acids inside cells allows measurement of their intracellular behavior with a unique pH‐dependent chemical shift signature. The intracellular longitudinal relaxation constant ( T 1 ) of these acids is shown to be up to four‐fold shorter than the corresponding extracellular T 1 . The result has a direct impact on the quantification of real‐time cellular kinetics.