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Download fileMechanistic and Structural Features of Protein Adsorption onto Mesoporous Silicates
journal contribution
posted on 2002-06-27, 00:00 authored by Joseph Deere, Edmond Magner, J. Gerard Wall, B. Kieran HodnettThe adsorption of cytochrome c onto a range of different mesoporous silicates (MPS) was studied. The materials
used, templated using both cationic and nonionic surfactants, have average pore-size diameters in the range
from 28 to 130 Å. Cytochrome c was found to bind to all MPS investigated, with the pore diameter of the
material, which was measured by N2 gas adsorption, being crucial to mesopore penetration. The adsorption
of a range of proteins with isoelectric points between 1 and 10 was investigated. For adsorption to occur, the
surface charges of the protein and of the MPS must be complementary, in addition to the requirement that the
pore diameter be sufficiently large. Pepsin at pH 6.5, for example, is negatively charged and does not adsorb
onto cyano-modified silicate whereas subtilisin, which is of a similar size and bears an overall positive charge,
is adsorbed. Using resonance Raman spectroscopy, cytochrome c was observed to occur in both high spin
and low spin states, in contrast to that in solution, where the protein is predominantly in the low spin state.
The presence of the high spin state may account for the enhanced peroxidative activity of the adsorbed protein.