Electrooptical determination of the isoelectric point of globular proteins: Cytochrome c adsorbed on montmorillonite nanoplates.

The purpose is to study the capability of the electric light scattering to determine the point of zero charge of native protein macromolecules adsorbed on colloid particles at low ionic strength and without using buffers. The chosen protein and particles are cytochrome c (cytC, globular haemoproteid) and montmorillonite (MM, negatively charged plate-like crystal). The pH-dependence of the electric polarizability γ(pH) in the range pH 6-11 shows minimum which coincides with the isoelectric point determined by measuring the electrophoretic mobility μ(pH) of the cytC-MM particles.

Isoelectric point of free and adsorbed cytochrome c determined by various methods.

The purpose is to determine the isoelectric point (IEP) pI of cytochrome c (cytC, a globular haemoproteid) adsorbed on montmorillonite (MM, plate-like colloid particles) by microelectrophoresis and to compare the pI value with pI9.44 measured by isoelectric focusing in gel with covalently linked ampholytes, and with pI10.0-10.

Adsorption of cytochrome c on montmorillonite nanoplates: protein concentration dependence.

Cytochrome c [cytC] is a mitochondrial hemoprotein functioning as electron carrier in the respiratory chain of the biological cells. Being adsorbed on colloid particles cytC can be introduced in the cells by phagocytoses. In the present work we study the adsorption of cytC on montmorillonite (MM) particles combining the electro-optic and electrophoretic techniques.

Adsorption of carboxymethyl cellulose on alumina particles.

The polyelectrolyte adsorption on colloid particles is often used for stabilization or flocculation of water suspensions. The aim of this work is to study the adsorption of carboxymethyl cellulose (CMC) on alumina (γ-Al2O3) colloid particles. The particles and polymer are chosen because of the capability of the metal-oxide ampholyte surface and the weak polyelectrolytes to alter their charge by pH.