Physicochemical properties and blood clearance of human serum albumin conjugated to different extents with dinitrophenyl groups.

Human serum albumin (HSA) conjugated to various extents with dinitrophenyl (DNP) groups and labelled with 125I was studied with regard to physicochemical properties and blood clearance after intravenous injection in mice. Increasing the degree of DNP conjugation increased the tendency to hydrophobic interaction, and increased the net negative charge. Heavily DNP-substituted HSA molecules tended to aggregate. The higher the degree of DNP substitution the faster was the conjugate eliminated from the circulation. Blood clearance was independent of serum complement, and was not affected by galactose, N-acetylglucosamine, mannose, alpha-methyl-D-mannoside, or fucose. It is proposed that the differences in blood clearance between the different DNP-HSA conjugates mainly depend upon differences in the tendency to hydrophobic interaction.