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A chromophoric bifunctional probe design that allows selective chiroptical sensing of cysteine in aqueous solution is introduced. The common need for chiral HPLC separation is eliminated which expedites and simplifies the sample analysis while reducing solvent waste. Screening of the reaction between six phenacyl bromides and the enantiomers of cysteine showed that cyclization to an unsaturated thiomorpholine scaffold coincides with characteristic UV and CD effects, in particular when the reagent carries a proximate auxochromic nitro group. The UV changes and CD inductions were successfully used for determination of the absolute configuration, enantiomeric composition and total concentration of 18 test samples. This assay is highly selective for free cysteine while other amino acids, cysteine derived small peptides and biothiols do not interfere with the chiroptical signal generation.
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Chiroptical sensing of homocysteine
The cyclization reaction between ortho -phthalaldehyde and l -homocysteine coincides with the generation of a pronounced positive CD signal at approximately 335 nm. Under identical conditions, other amino acids including cysteine produce very weak CD responses. This unusual substrate specificity allows accurate chiroptical analysis of the enantiomeric composition of homocysteine samples in the presence of cysteine without the need for time-consuming chromatographic separation. This significantly simplifies and speeds up ee determination at reduced solvent waste production.
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- Award ID(s):
- 1764135
- PAR ID:
- 10233082
- Date Published:
- Journal Name:
- Organic & Biomolecular Chemistry
- Volume:
- 18
- Issue:
- 42
- ISSN:
- 1477-0520
- Page Range / eLocation ID:
- 8629 to 8632
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0OB01798A
