Large-ligand adsorption to membranes: I. Linear ligands as a limiting case

It is shown that the usual evaluation of binding data in terms of linear Scatchard plots or using simple mass-action equations is not applicable to the binding of ligands covering more than one receptor on a membrane. As a first step in a general treatment of large-ligand adsorption to membranes, a simple formula is derived which applies to linear chain molecules binding to a membrane without cooperative interactions. The formula may be considered as an extension to surface problems of the well-known one-dimensional treatment of Mc Ghee and Von Hippel (Mc Ghee, J.D. and Von Hippel, P.H. (1974) J. Mol. Biol. 86, 469–489). Being applied to non-linear ligand molecules, our treatment yields a lower limit estimate of the stoichiometric number.