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Chemoselective detection and discrimination of carbonyl‐containing compounds in metabolite mixtures by 1 H‐detected 15 N nuclear magnetic resonance
Author(s) -
Lane Andrew N.,
Arumugam Sengodagounder,
Lorkiewicz Pawel K.,
Higashi Richard M.,
Laulhé Sébastien,
Nantz Michael H.,
Moseley Hunter N.B.,
Fan Teresa W.M.
Publication year - 2015
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4199
Subject(s) - chemistry , adduct , metabolite , mass spectrometry , aldehyde , chemical shift , proton nmr , nmr spectra database , carbon 13 nmr , stereochemistry , chromatography , organic chemistry , spectral line , biochemistry , physics , astronomy , catalysis
NMR spectra of mixtures of metabolites extracted from cells or tissues are extremely complex, reflecting the large number of compounds that are present over a wide range of concentrations. Although multidimensional NMR can greatly improve resolution as well as improve reliability of compound assignments, lower abundance metabolites often remain hidden. We have developed a carbonyl‐selective aminooxy probe that specifically reacts with free keto and aldehyde functions, but not carboxylates. By incorporating 15 N in the aminooxy functional group, 15 N‐edited NMR was used to select exclusively those metabolites that contain a free carbonyl function while all other metabolites are rejected. Here, we demonstrate that the chemical shifts of the aminooxy adducts of ketones and aldehydes are very different, which can be used to discriminate between aldoses and ketoses, for example. Utilizing the 2‐bond or 3‐bond 15 N‐ 1 H couplings, the 15 N‐edited NMR analysis was optimized first with authentic standards and then applied to an extract of the lung adenocarcinoma cell line A549. More than 30 carbonyl‐containing compounds at NMR‐detectable levels, six of which we have assigned by reference to our database. As the aminooxy probe contains a permanently charged quaternary ammonium group, the adducts are also optimized for detection by mass spectrometry. Thus, this sample preparation technique provides a better link between the two structural determination tools, thereby paving the way to faster and more reliable identification of both known and unknown metabolites directly in crude biological extracts. Copyright © 2015 John Wiley & Sons, Ltd.