Optimization of protein conjugation using an aldehyde derivatized bifunctional chelating agent

The covalent attachment of the bifunctional chelating agent 2-(p-aminobenzyl)-1,3-propanediamine-N,N,N′,N′-tetraacetic acid to proteins through a new linking arm containing an aldehyde function for the purpose of labeling proteins and monoclonal antibodies with radiometals was studied. The number of protein-bound chelating groups was measured by various techniques after labeling the conjugate with 111In. The effect of various parameters such as aldehyde-chelate concentration, pH, temperature, protein concentration and concentration of sodium cyanoborohydride on the rate and extent of protein conjugation have been examined.