AQC (6-Aminoquinolyl-N-hydroxysuccinimidyl carbamate)
6-Aminoquinolyl-N-hydroxysuccinimidyl carbamate (or as short name: AQC or AccQ-Tag)
is a highly efficient fluorogenic reagent used for the pre-column derivatization of primary and secondary amines. It is very important in modern bioanalytics for the high-sensitivity detection of amino acids and peptides using High-Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS).
Chemical Mechanism and Reaction of AQC:
AQC is an activated carbamate that reacts rapidly with amino groups to form stable, asymmetric derivatives of urea.
- Rapid Kinetics: The reaction is nearly instantaneous, occurring within seconds.
- Optimal Conditions: Derivatization typically requires an alkaline environment with a pH between 8.2 and 10.1 (often achieved with borate buffer).
- Byproducts: Excess reagent that does not react with amines is slowly hydrolyzed into 6-aminoquinoline (AMQ), N-hydroxysuccinimide, and carbon dioxide. Because AMQ fluoresces only weakly at the target wavelengths, it does not significantly interfere with the analysis of the amino acid adducts.
Analytical Advantages:
AQC offers several superior features compared to traditional reagents like OPA (ortho-phthalaldehyde) or PITC (phenylisothiocyanate):
- High Sensitivity: It enables detection at femtomole to low picomole levels.
- Exceptional Stability: Derivatized samples are extremely stable and can be stored at room temperature for up to one week without significant signal loss, facilitating automated batch processing.
- Broad Compatibility: It effectively labels both primary and secondary amines.
- Mass Spectrometry Enhancement: Beyond fluorescence, AQC tagging improves the ionization efficiency of analytes for liquid chromatography-mass spectrometry (LC-MS) applications.
Diverse Applications:
Due to its reliability, AQC is utilized across various scientific and industrial sectors:
- Food Science: Analyzing amino acid composition in infant formulas, wine, grains, and animal feed.
- Authentication: Screening the source of commercial gelatins (e.g., distinguishing bovine from porcine or fish) to meet dietary and religious requirements.
- Biotechnology: Peptide mapping and protein sequence analysis, particularly for complex drugs like glatiramer acetate.
- Clinical Research: Targeted metabolomics for discovering disease biomarkers in physiological fluids such as blood plasma.
- Stereochemistry: When paired with chiral stationary phases, AQC allows for the separation of D- and L-amino acid enantiomers.
Safety and Handling:
AQC is typically provided as a solid powder and should be stored under inert gas in a refrigerator. It is classified as a hazardous substance (Skin/Eye Irritant, Category 2), so standard laboratory safety protocols, including the use of gloves and eye protection, are mandatory. High-quality versions of the reagent (≥99% purity) is delivered from our company
References:
https://www.ncbi.nlm.nih.gov/pubmed/16586471
http://pubs.rsc.org/en/content/articlelanding/2017/qm/c7qm00076f#!divAbstract