• 1 January 1977
    • journal article
    • research article
    • Vol. 33  (1) , 11-16
Abstract
Investigation of the binding of .epsilon.-DNP [dinitrophenyl]-L-lysine to the subunits (Fab'') of bovine colostral Ig[immunoglobulin]G1 anti-DNP over a wide range of temperatures yielded non-linear van''t Hoff plots with curvatures indicative of large positive heat capacity changes. Thermodynamic functions, calculated using a non-linear least-squares procedure, revealed an enthalpy-entropy compensation mechanism for binding. While the enthalpy factor was the driving force for the hapten-subunit interaction(s) at low temperatures, the entropy factor assumed greater importance with increasing temperatures. The enthalpy-entropy compensation plot for the interaction of .epsilon.-DNP-L-lysine with bovine colostral Fab'' anti-DNP, intact anti-DNP IgG1 and rabbit IgG anti-DNP revealed a constant compensation temperature of 27.degree. C which might indicate a single kind of protein-solvent conformation.