BINDING OF INDOCYANINE GREEN (ICG) TO NORMAL HUMAN SERUM PROTEIN

Abstract

Binding of indocyanine green (ICG) to human serum protein was investigated using by gel filtration, electrophoresis and ultracentrifugation.
ICG bound to α-lipoprotein (α-Lp), β-lipoprotein (β-Lp), and albumin (Alb) and α₂-globulin(α₂Gl) of human serum. At low concentration of ICG in serum (1×10^-5M) it bound obviously to β-Lp. At high concentration (1×10^-3M) it bound to β-Lp, α-Lp, and Alb and α₂Gl. There were aproportional relation between binding of ICG to each protein and ICG concentration in serum.
Binding of ICG to serum protein revealed two groups of binding sites by Rosethal plot withstepwise elution method. One was a high-affinity and low-capacity, and the other was a low-affinityand high-capacity. The binding of sulfobromophthalein to human serum revealed one group ofbinding site as high-affinity and low-capacity.