| We
are using sum frequency generation (SFG) vibrational spectroscopy and
atomic force microscopy (AFM) to investigate molecular structures of
various protein molecules at different interfaces in situ. SFG is a
powerful and versatile in situ nonlinear optical surface/interface
probe which not only permits identification of surface/interface
molecular species, but also provides information about
surface/interface chemical structure. It will provide vibrational
spectra of surfaces and interfaces with submonolayer sensitivity. AFM
has been developed into a powerful tool to probe surface/interface
structures with excellent spatial resolution through topographic,
friction, or phase images. Proteins currently being studied in our
group include albumin, fibrinogen, factor XII, fibrinectin, ubiquintin,
and heat shock proteins. Homo-polypeptides and hetero-polypeptides are
also investigated, serving as model molecules. These proteins and
peptides are examined at various interfaces, including solid/protein
solution interfaces, solid/water interfaces, solid/hydrophobic liquid
interfaces, and solid/air interfaces. We have successfully demonstrated
by SFG and AFM that a molecular level understanding of protein
conformation changes at different interfaces is feasible. We hope to
correlate the protein conformation changes observed by SFG and AFM to
structures of native proteins, properties of different interfaces, and
pH values of protein solutions. We will follow the kinetics of protein
conformation changes at different interfaces. |
[1].
J. Wang, S. M. Buck, M. A. Even, Z. Chen, ?Molecular Responses of
Proteins at Different Interfacial Environments Detected by Sum
Frequency Generation Vibrational Spectroscopy?, J. Am. Chem. Soc., 124,
13302 (2002)
[2]. J. Wang, Z. Paszti, M. A. Even, Z. Chen,
?Measuring Polymer Surface Ordering Differences in Air and in Water by
Sum Frequency Generation (SFG) Vibrational Spectroscopy?, J. Am. Chem.
Soc., 124, 7016 (2002)
[3]. J. Wang, S. E. Woodcock, S. M. Buck, C.
Y. Chen, Z. Chen, ?Different Surface Restructuring Behaviors of
Polymethacrylates Detected by SFG in Water?, J. Am. Chem. Soc., 123,
9470 (2001)
[4]. J. Wang, C. Y. Chen, S. M. Buck, Z. Chen,
?Molecular Chemical Structure on Poly(methyl methacrylate) (PMMA)
Surface Studied by Sum Frequency Generation (SFG) Vibrational
Spectroscopy?, J. Phys. Chem. B, 105, 12118 (2001)
[5]. Z. Chen, Y.
R. Shen. G. A. Somorjai, ?Studies of Polymer Surfaces by Sum Frequency
Generation Vibrational Spectroscopy?, Ann. Rev. Phys. Chem., 53, 437,
(2002)
[6]. C. Y. Chen, J. Wang, S. E. Woodcock, Z. Chen, ?Surface
Morphology and Molecular Chemical Structure of Poly(n-butyl
methacrylate)/Polystyrene Blend Studied by Atomic Force Microscopy
(AFM) and Sum Frequency Generation Vibrational Spectroscopy (SFG)?,
Langmuir, 18, 1302 (2002)
[7]. C. Y. Chen, J. Wang, M. A. Even, Z.
Chen, ?Sum Frequency Generation (SFG) Vibrational Spectroscopy Studies
on ?Buried? Polymer/Polymer Interfaces?, Macromolecules, 35, 8093 (2002)
[8].
C. Y. Chen, M. A. Even, J. Wang, Z. Chen, ?Sum Frequency Generation
(SFG) Vibrational Spectroscopy Studies on Molecular Conformation of
Liquid Polymers Poly(Ethylene Glycol) (PEG) and Poly(Propylene Glycol)
(PPG) at Different Interfaces?, Macromolecules, 35, 9130 (2002)
[9].
J. Wang, S. M. Buck, Z. Chen, ?Sum Frequency Generation (SFG)
Vibrational Spectroscopy Studies on Protein Adsorption?, J. Phys. Chem.
B, 106, 11666 (2002)
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