Amino acid end-group in commercial heparin. II. Reaction kinetics of the amino end groups with 2,4,6-trinitrobenzenesulfonic acid

Three different commercial heparins were trinitophenylated with 2,4,6-trinitrobenzenesulfonic acid (TNBS) under aqueous conditions. The reaction kinetics of amino groups in heparin with TNBS showed that the reactivities of amino groups were significantly different for free amino groups on heparin, compared to reactivities in peptides and amino acid residues attached to heparin molecules. With TNBS, unreactive amino groups were always present during the reaction.