Measurement of the binding of human colipase to human lipase and lipase substrates.

Equilibrium partition in an aqueous two-phase system was the method used for quantitative determinations of the binding between human colipase and human lipase and three triacylglycerol substrates: Intralipid tributyrin and triolein. The measurements were performed in a dextran/polyethyleneglycol system at pH 7.0 in the presence of 2 mM sodium taurodeoxycholate and 150 mM NaCL. The binding of colipase to lipase had a dissociation constant Kd = 4.8 . 10(-8) M. The dissociation constants for the binding of colipase to Intralipid, tributyrin and triolein were found to be 2.10(-7) M, 4.8 . 10(-8) M and 6.2 . 10(-8) M, respectively.