Partition Mechanism of Protein Adsorption onto Bead 3-Phenoxy-2-hydroxypropyl Cellulose Role of External Surface of Cellulose Particles
A. Breier, P. Gemeiner, and D. Hagarová
lnstitute of Molecular Physiology and Genetics, Slovak Academy of Sciences,
SK-833 34 Bratislava
Abstract: Adsorption of proteins onto 3-phenoxy-2-hydroxypropyl derivatives of bead cellulose (PHPC) was studied. Partition coefficient p characterizing the material balance of adsorption in equilibrium was found to show a tendency to increase with the increasing protein relative molecular mass. Affinities of protein-ligand interactions were found to follow a similar tendency because apparent dissociation constants of these interactions (K-d as a reciprocal parameter) decreased with the increasing protein relative molecular mass. Thus, size-exclusion properties of the original bead cellulose did not control adsorption onto hydrophobized PHPC. Fluorescence microscopy of PHPC particles after adsorption of fluorescein (as an amphiphilic fluorescent label) revealed localization of the label on the external surface of cellulose particles. The 3-phenoxy-2-hydroxypropyl (PHP) groups should be localized predominantly at the external surface of cellulose particles too, accordingly, steric problems of fluorescein (as a low-molecular mass label) in penetration into the internal space of bead cellulose macroporous structure are improbable. Open microenvironment around the PHP groups localized on the external surface of cellulose particles could not be an effective steric barrier in the contact with protein molecules. This may be considered as explanation for the lack of site exclusion properties in the control of protein adsorption onto the PHPC.
Full paper in Portable Document Format: 483a141.pdf
Chemical Papers 48 (3) 141–145 (1994)