Substrate‐Specific Amino Acid Sensing Using a Molecular d/ l‐Cysteine Probe for Comprehensive Stereochemical Analysis in Aqueous Solution

Abstract

The appearance of d-amino acids in mammals and humans has important implications in the life sciences. d/l-Amino acid mixtures play a key role in human physiology and pathology; thus, the introduction of artificial receptors for the real-time quantification of both the concentration and d/l composition of amino acids is very promising for the study of biological processes and for the diagnosis and treatment of diseases. We now report a sensing assay that is compatible with aqueous solutions and allows fast determination of the absolute configuration, enantiomeric composition, and overall amount of cysteine at micromolar concentrations. The method relies on fast UV and CD measurements, which provide accurate stereochemical information on samples covering a wide concentration range and drastically different d/l-cysteine ratios in simulated body fluids. Competition experiments show that other amino acids and biothiols do not interfere with the cysteine-targeted sensing.

Click chemistry enables quantitative chiroptical sensing of chiral compounds in protic media and complex mixtures

“…Few examples of asymmetric reaction analysis with sensors operating on the principles of dynamic covalent chemistry 8–11 , metal complex coordination 12 , and supramolecular chemistry 13–15 to recognize a chiral target compound and to generate quantifiable ultraviolet (UV), fluorescence, and circular dichroism (CD) signals have been reported 16–18 . Comprehensive chirality sensing (CCS), i.e., determination of the absolute configuration, yield, and enantiomeric excess ( ee ), of crude asymmetric reaction mixtures via irreversible covalent product fixation has been largely neglected to date 19 .…”

Optische Chiralitätssensorik mit ligandenfreien, weit verbreiteten Cobaltsalzen

“…So konnten wir beide Messungen auf einmal mit einer einzigen Probe bei m m Konzentration (ein Experiment pro Probe) erhalten. Da optische Sondierungen vermehrt als leistungsstarke Alternative zu chromatographischen Methoden für asymmetrische Reaktionsanalysen und stereoselektive Quantifizierungen von Biomarkern eingesetzt werden, untersuchten wir die Möglichkeit der gleichzeitigen Bestimmung der absoluten Konfiguration, Enantiomerenzusammensetzung und Konzentration. Die UV/CD‐Sondierung von neun Proben mit unterschiedlicher Konzentration und Enantiomerenzusammensetzung von 25 ermöglichte die zuverlässige Identifizierung des Überschuss‐Enantiomers basierend auf dem Vorzeichen des ICD‐Signals (Tabelle ).…”

Stereochemical analysis of chiral amines, diamines, and amino alcohols: Practical chiroptical sensing based on dynamic covalent chemistry

“…bond formation with a chiral analyte to generate a CD signal that can be used for absolute configuration and ee determination have been developed by several groups. [44][45][46][47][48][49][50][51][52] Nevertheless, reversible Schiff base formation with chiral amines has become a very popular and highly successful CD sensing strategy. 27,28,30,39,41,53,54 We now wish to report a highly practical method that allows chiroptical ee analysis of a wide range of amines and amino alcohols using an inexpensive commercially available benzaldehyde derivative as probe.…”

“…The large majority of CD sensing assays introduced so far relies on the formation of supramolecular assemblies, metal coordination complexes, hydrogen bond adducts, or dynamic covalent chemistry (DCC) . In addition, stereodynamic probes that undergo irreversible covalent bond formation with a chiral analyte to generate a CD signal that can be used for absolute configuration and ee determination have been developed by several groups . Nevertheless, reversible Schiff base formation with chiral amines has become a very popular and highly successful CD sensing strategy .…”