Covalent coupling of bilirubin to albumin

A method for covalent coupling of bilirubin to albumin is described. Human serum albumin-bilirubin (1:1 complex) has been treated with water soluble carbodiimide in order to obtain covalent coupling of bilirubin to albumin. The reaction conditions have been varied with respect to pH, reaction time and concentration of reagent to obtain the optimal coupling. The prepared albumin-bilirubin compounds were investigated by spectrophotometry, gel filtration and gel electrophoresis to ascertain the covalent nature of the bond and to characterize the products further. Gel electrophoresis and gel filtration showed that a monomer fraction could be prepared, and this fraction was a suitable material for further studies.