Multiple-site binding nonequivalent sites

For the case of multiple-site bindings involving a biomacromolecule with n nonequivalent, but not interacting/cooperative sites, the macromolecule is considered to display m classes of independent sites (n m 1), each class i (1 i m) having Uj sites with an intrinsic binding constant, Ki (Klotz and Hunston, 1971). The total number of sites occupied by a ligand per macromolecule will simply be the sum of the number of sites of each class occupied per macromolecule ([A] will be written simply as A for the clarity here), i.e.  

The equation can be rewritten in Klotz form (double reciprocal) as 

The summation is carried out from i = 1 to m and Xni = n (total number of sites). 

The v versus [A] plot according to the above equation generally produces a biphasic curve consisting of two approximately linear segments with the following characteristics  

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