Influences of metal ions on the reaction of amino and imino acids with fluorogenic reagents.
When a twofold excess of metal ions (Cu2+, Ni2+, Zn2+, Mg2+, Ca2+, Fe3+, and Al3+) was added to a reaction medium of amino acids (1-50 microM each) with the fluorogenic reagents NBD-F (4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole), DNS-Cl (5-N,N-dimethylaminonaphthalenesulfonyl chloride), OPA (o-phthalaldehyde), and fluorescamine (4-phenylspiro[furan-2(3H),1'-phthalan]-3,3'-dione), a reduction of derivatization was observed. The effect was especially marked on the reaction with NBD-F. The derivatization of His and Asp with DNS-Cl and fluorescamine and of His with OPA was suppressed by Cu2+ and/or Ni2+. The suppression by the metal ions can be overcome by the addition of EDTA to the reaction medium. For determination of a small amount of amino and imino acids (less than microM) the addition of a chelating reagent to biological samples is recommended before derivatization with these electrophilic reagents.
D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives; D000596:Amino Acids / Q000032:analysis*; D003619:Dansyl Compounds; D004492:Edetic Acid; D005450:Fluorescamine; D005456:Fluorescent Dyes; D007098:Imino Acids / Q000032:analysis*; D008670:Metals; D013050:Spectrometry, Fluorescence; D009764:o-Phthalaldehyde
D000596:Amino Acids; D003619:Dansyl Compounds; D005456:Fluorescent Dyes; D007098:Imino Acids; D008670:Metals; C032930:7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole; D005450:Fluorescamine; D009764:o-Phthalaldehyde; D004492:Edetic Acid; D009327:4-Chloro-7-nitrobenzofurazan; C029038:dansyl chloride