(194b) Structure of Myoglobin Confined in Nanoporous Silica

There is considerable interest in the use of protein immobilization in porous hosts to address challenges in biotechnology and therapeutics. Hence, there is a need to develop a more thorough understanding of the fundamental behavior of proteins in confinement.  Pore surface properties such as charge or hydrophobicity are known to dramatically affect the behavior and structure of interacting proteins.^1,2  Our studies of confinement effects in nanoporous particles has shown that geometric properties such as surface curvature play a significant role, and pores of high curvature may stabilize the native protein structure.²  This could protect enzymes from extreme environmental conditions.³  While these results are promising, they only paint a partial picture of the structure and behavior of confined proteins, and need to be used in conjunction with other techniques to provide a clearer molecular understanding.  This investigation attempts to further the understanding of a model system – myoglobin in nanoporous silica SBA-15 – by determining the overall structure and physicochemical properties of confined myoglobin.  Structural information is obtained through the use of direct probing techniques such as small angle neutron scattering (SANS) to observe whole protein structural parameters, paired with previously obtained FTIR secondary structural information,³ and using these parameters in a geometric model that evaluates the packing of globular proteins, modeled as ellipsoids, in cylindrical channels.⁴  The information obtained in this study provides further insight into the fundamentals of protein confinement.

References:

1. Yuan L, Yu Q, Li D, Chen H. Surface Modification to Control Protein/Surface Interactions. Macromolecular Bioscience. 2011;11(8):1031–1040. doi:10.1002/mabi.201000464.
2. Sang L-C, Coppens M-O. Effects of surface curvature and surface chemistry on the structure and activity of proteins adsorbed in nanopores. Physical Chemistry Chemical Physics. 2011;13(14):6689. doi:10.1039/c0cp02273j.
3. Lynch M., Siefker J., Coppens M-O. Confinement Protection Effects of Mesoporous Silica SBA-15 On Myoglobin, in an Environment Inspired by the Groel/ES Chaperonin System. AIChE Annual Meeting. 2012.
4. Sang L-C, Vinu A, Coppens M-O. General Description of the Adsorption of Proteins at Their Iso-electric Point in Nanoporous Materials. Langmuir. 2011;27(22):13828–13837. doi:10.1021/la202907f.