Fluorescein aldehyde [5-FAM aldehyde]

Fluorescein aldehyde is a reactive fluorescent dye that can react with an amine, hydrazine or hydroxylamine. Fluorescein is the most widely used green fluorescent dye. Aldehyde group is reactive toward amines, hydrazide or hydroxylamine groups from pH 5-9. Unlike amine reactive succinimidyl ester group (NHS), aldehyde can react with N-terminal amine groups at acidic pH, a condition sometimes required for certain bioconjugation reactions. Aldehyde reacts with amine group to form an intermediate Schiff bond. Further reduction with hydride will form a stable C-N bond. Reaction between aldehyde and other groups allows site-specific conjugation and labeling of fluorescein dyes to desired position on targeted molecules. Conjugated fluorescein dye can be easily detected by a common fluorescence instrument under FITC channel.