COMPETITIVE ADSORPTION OF HIGH-MOLECULAR-WEIGHT KININOGEN AND FIBRINOGEN FROM BINARY-MIXTURES TO GLASS-SURFACE

An investigation of adsorption from binary mixtures of fibrinogen and high molecular weight kininogen (KK) to glass is reported. Experiments were performed using radioiodinated proteins in which the adsorption of each protein was measured from serial dilutions of mixtures having a ratio of the proteins approximately the same as in plasma (fibrinoge n in excess). Fibrinogen adsorption passes through a maximum as soluti on concentration increases, analogous to its behavior in plasma as rep orted previously (Brash, J. L.; ten Hove, P. Thromb. Haemostasis, 1984 , 51, 326). HK adsorption increases monotonically with concentration s uch that fibrinogen is virtually excluded from the surface at the high est concentrations even though present in large excess. A kinetic mode l is developed in which initially adsorbed fibrinogen can either desor b spontaneously, relax to an irreversibly bound state, or exchange wit h HK. The model solution is obtained in terms of the ratio of the rate constants for exchange and relaxation, k(ex)/k(1)(') and is independe nt of the nature of the available surface function. Data fits to the m odel are excellent and give essentially invariant values of k(ex)/k(1) (') for different ratios of the two proteins in solution. The results of this study emphasize the importance of surface relaxation in compet itive protein adsorption.