Identification of Single-Molecule Catecholamine Enantiomers Using a Programmable Nanopore
Wendong JiaChengzhen HuYuqin WangYao LiuLiying WangShanyu ZhangQiang ZhuYuming GuPanke ZhangJing MaHong‐Yuan ChenShuo Huang
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Enantiomers, chiral isomers with opposite chirality, typically demonstrate differences in their pharmacological activity, metabolism, and toxicity. However, direct discrimination between enantiomers is challenging due to their similar physiochemical properties. Following the strategy of programmable nanoreactors for stochastic sensing (PNRSS), introduction of phenylboronic acid (PBA) to a Mycobacterium smegmatis porin A (MspA) assists in the identification of the enantiomers of norepinephrine and epinephrine. Using a machine learning algorithm, identification of the enantiomers has been achieved with an accuracy of 98.2%. The enantiomeric excess (ee) of a mixture of enantiomeric catecholamines was measured to determine the enantiomeric purity. This sensing strategy is a faster method for the determination of ee values than liquid chromatography-mass spectrometry and is useful as a quality control in the industrial production of enantiomeric drugs.Keywords:
Enantiomeric excess
The enantiomeric excess (e.e.) determination of organic amines and dipeptides has been examined using ESI and FAB mass spectrometry. Here, an equimolar amount of labeled and unlabeled enantiomeric host pair compounds is mixed with a given e.e.-unknown guest compound. This is called the enantiomer labeled (EL)-host method. The enantiomeric host pairs employed were (1) chiral podands having galactose end-groups and (2) chiral crown ethers. Three sets of the Ie (intensity excess)-e.e. plot showed excellent linear relationships, indicating that the e.e.-value of e.e.-unknown amine compounds can be determined by the simple ESIMS or FABMS coupled with the EL-host method, within the mean error of 1.5-4%e.e.
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This note describes an easy way to calculate percentage enantiomeric ratios from enantiomeric excesses. To calculate the percentage of the major enantiomer, simply take the enantiomeric excess, add 100 and divide by 2.
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Direct determination of both the enantiomeric purity and absolute configuration of timolol was accomplished utilizing 1H NMR (400 MHz) spectroscopy with fast diamagnetic chiral solvating agent to dissimilarly perturb the spectra of enantiomeric solutes. Nonequivalence behavior was studied for all variables that affect populations and intrinsic spectra of the diastereomeric solvates. Optimization of the experimental conditions in terms of probe temperature, substrate concentration and solvating agent to substrate molar equivalents provided resolved enantiomeric signals suitable not only for chiral recognition but also for quantification. Enantiomeric impurity was determined on the basis of relative intensities of the tert-butyl methyl protons resonances; the assignment of enantiomeric configuration was based on the relative field positions of these resonances. The analysis of synthetic mixtures of the enantiomers by the proposed NMR method resulted in assay values which agreed closely with the known quantities of each enantiomer in mixtures tested. The mean +/-SD recovery values for the (R)-(+)-enantiomer was 100.0+/-1.6% of added antipode (n = 8). The optically pure enantiomers were used to establish the minimum detection limits of0.1%. The developed methodology represents a rapid and powerful tool for regulatory analysis.
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Abstract (R)‐ and (S)‐2,3‐dihydroxy‐3‐methylbutyl p‐toluenesulfonate, used as building blocks for vitamine D 3 metabolites and carotenoids, respectively, were resynthesized since differing melting points and optical rotations are reported in the literature. The given data of the (S)‐enantiomer could be corrected. A method for the determination of the enantiomeric purity was elaborated using the influence of a chiral lanthanide shift reagent on the 1 H‐n.m.r. spectra of these compounds. By this way it was shown that both compounds exhibit an enantiomeric excess of more than 94%. The (S)‐enantiomer was synthesized according to an improved synthetic scheme starting from L‐serine.
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It is shown that chromatography with achiral phases of non-racemic mixture of binaphthol can furnish fractions which differ in enantiomeric excess. The first fraction contains one pure enantiomer i.e., has an enantiomeric excess (ee %) close to 100% and the following fractions have an ee % close to 0% (racemic mixture). As a consequence, such chromatography may be used to enrich a non-racemic mixture of binaphthol in one enantiomer. In this paper a model is proposed allowing us to calculate with good accuracy the experimental elution curves. This simple model is capable of using only a few chromatographic experiments to predict the enantiomeric enrichment of a non-racemic mixture and to calculate precisely the retention time of each fraction. © 1996 Wiley-Liss, Inc.
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Fraction (chemistry)
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Abstract Just 20 % of chiral synthetic drugs are used as pure stereoisomers 1) , although it is known from numerous examples that optical isomers may have quite different biological effects 2) . Therefore the enantiomeric purity is an important probe for monitoring the quality of drugs. The availability of reliable analytical techniques for the correct determination of enantiomeric compositions is therefore becoming increasingly important. Such a method should allow us to deal successfully with the determination of small enantiomeric impurities.
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Methyldopa
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A colour indicator for the full range of enantiomeric excess (-100%-->100% ee) is presented which is based on visual colour inspection of a liquid crystal doped with the analyte, i.e. the methyl ester of amino acid phenylglycine, providing the enantiomeric excess and allowing the assignment of the major enantiomer.
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Enantiomeric excess
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Proton NMR
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Enantiomeric excess
Inert
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Stereospecificity
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Carbon skeleton
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