Adsorption and binding of AmpliTaq® DNA polymerase on the clay minerals, montmorillonite and kaolinite

Adsorption at equilibrium and binding of AmpliTaq® DNA polymerase (TDP) on clay minerals, two montmorillonites (W–M and Ap–M) and a kaolinite (K), were studied. Equilibrium adsorption isotherms were of the L type, and a plateau was reached with Ap–M and K, whereas no plateau was obtained with W–M. Adsorption of TDP was most rapid on W–M, maximal at pH 6 on all clays, and appeared to involve hydrophobic interactions between the clays and TDP. The amounts of TDP adsorbed and bound on the clays were higher on W–M than on Ap–M and K and occurred only on the external surfaces of the clays. Fourier-transform infrared spectra, SDS–PAGE and scanning electron microscopy of both pure TDP and the W–M–TDP complex showed the presence in the commercial TDP of microspheres (about 100 nm in diameter) of unidentified material, which could influence the adsorption-binding of TDP on clays.