Hepatic binding protein (HBP) is a membrane receptor that binds and transports plasma glycoproteins from hepatic blood to hepatocellular lysosomes. We have characterized the in vitro binding of Tc-99m galactosyl-neoglycoalbumin (Tc-NGA), a synthetic HBP ligand, to liver membrane. Structural modifications of NGA resulted in the alteration of the equilibrium constant, K(A), and the forward-binding rate constant, k(b). Binding was second-order; the relative amount of membrane-bound NGA depended on the initial concentrations of ligand and membrane. Membrane displacement studies, using carrier ligands in contrast to previously bound Tc-NGA or I-NGA, correlated with the binding characteristics of a native HBP ligand, asialo-orosomucoid. We used computer simulation to study the detectability of the changes in HBP concentration at different values of k(b). The simulations indicated that radiopharmacokinetic sensitivity to alterations in [HBP] should be possible using a neoglycoalbumin preparation with a carbohydrate density within the range of 15 to 25 galactose units per albumin molecule.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Nuclear Medicine|
|State||Published - Jan 1 1984|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging