Abstract: The reducing terminal of marine sulfated polysaccharide(911) was used to selectively insert primary and secondary amines by reductive amination. 911 was bounded to 4-(2-aminoethylphenol), followed by labeling the 911-Tyr with fluorescein-5-isothiocyanate(FITC) at the secondary amino group. High-performance size-exclusion chromatography(HPSEC), ultraviolet/visible(UV-Vis) spectroscopy and nuclear magnetic resonance spectroscopy(NMR) demonstrated the binding of tyramine to 911 and the labeling of FITCto 911-Tyr respectively. Furthermore, +¹H NMRspectra and UV-Vis spectra revealed about 60% binding of tyramine to 911 and about 80% labeling of FITCto 911-Tyr. The anticoagulant activity of labeled fluorescent compound exhibited 13.40 U/mg equivalent to that of unlabled 911. In addition, the labeled compound was demonstrated to fluorescently stain lymphocytes without any cytotoxity. Taken together, the selectively "end point attached" method might be widely used for fluorecent labeling to those polysaccharides with reducing terminal.

Key words: Sulfated polysaccharide(911), Reductive amination, Fluorescent labeling