Use of hydrophobic affinity partitioning as a method for studying various conformational states of the human alpha-macroglobulins.

The serum proteins alpha 2-macroglobulin and pregnancy zone protein undergo major conformational changes when complexed with proteinases. It is shown that the changes in delta log Kmax determined by hydrophobic affinity partitioning is a measure of the extent of changes in the conformation of these alpha-macroglobulins. We introduce a new term for the changes of surface hydrophobicity in a protein as delta log Kacc. This defines the difference of delta log Kmax between a modified and an unmodified conformational state of a specific protein and can be useful as a parameter to describe the apparent conformational changes in the protein.