ANTIGENICITY OF 5-HYDROXYINDOLE-3-ACETIC ACID, A DERIVATIVE OF SEROTONIN: I. PREPARATION OF PROTEIN CONJUGATES OF 5-HYDROXYINDOLE-3-ACETIC ACID

Abstract

5-Hydroxyindole-3-acetic acid (5HIAA) was coupled to human, bovine, and rabbit serum albumins, to bovine γ-globulins, and to ε-aminocaproic acid (ACA) through the formation of peptide bonds. For this purpose N,N′-dicyclohexylcarbodiimide was used to prepare the intermediate acid anhydride of 5HIAA, which was subsequently reacted with the amino groups of proteins or ACA. Evidence is presented for the coupling of (i) about 18 residues of 5HIAA per molecule of albumin, (ii) about 30 residues per globulin molecule, and (iii) 1 residue per molecule of ACA.