Tetramethylrhodamine (TMR, TRITC) has been a widely used fluorophore for preparing bioconjugates, especially fluorescent antibody and avidin derivatives used in immunochemistry. Under the name TAMRA, the carboxylic acid of 5-TAMRA has also achieved prominence as a dye for labeling peptides and proteins. 5-TAMRA-protein conjugates are suitable for immunofluorescent staining, in situ hybridization, flow cytometry and other biological applications. The kit has all essential components for performing the conjugation reaction and for purifying the 5-TAMRA-protein conjugates.