Surface-induced conformational

Kim, D.H. et al.. Surface-induced conformational changes in poly(3-hexylthiophene) monolayer films, Langmuir 21, 3203-3206, 2005. 

The paper describes some of our studies of protein adsorption on solid surfaces. An emphasis is made on newly developed experimental techniques and on recent biological model experiments. We therefore discuss the use of a wettability gradient along a solid surface to Investigate, In a convenient way, the Influence of surface energy on the adsorption of protein molecules. The behavior of the complement system at solid surfaces Is also discussed, with special attention to surface Induced conformational changes of human complement factor 3. 

Roach, P Earrar, D. Perry, C. C. Interpretation of protein adsorption surface-induced conformational changes. J. Am. Chem. Soc., 2005, 727(22), 8168-8173. 

This area of research is still at its beginning and many aspects are not resolved. This includes in particular the structure and conformation of polymers at an interface as well as the modification of polymer dynamics by the interface. We have given several examples of the potential of surface and interface analytical techniques. They provide information on surface roughness, surface composition, lateral structure, depth profiles, surface-induced order and interfacial mixing of polymers on a molecular and sometimes subnanometer scale. They thus offer a large variety of possible surface and interface studies which will help in the understanding of polymer structure and dynamics as it is modified by the influence... 

Recent work in our laboratory has shown that Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) can be used routinely to measure vibrational spectra of a monolayer on a low area metal surface. To achieve sensitivity and resolution, a pseudo-double beam, polarization modulation technique was integrated into the FT-IR experiment. We have shown applicability of FT-IRRAS to spectral measurements of surface adsorbates in the presence of a surrounding infrared absorbing gas or liquid as well as measurements in the UHV. We now show progress toward situ measurement of thermal and hydration induced conformational changes of adsorbate structure. The design of the cell and some preliminary measurements will be discussed. 

Michael KE, Vemekar VN, Keselowsky BG, Meredith JC, Latour RA, Garcia AJ (2003) Adsorption-induced conformational changes in fibronectin due to interactions with well-defined surface chemistries. Langmuir 19 8033-8040... 

The influence of adsorption on the structure of a -chymotrypsin is shown in Fig. 10, where the circular dichroism (CD) spectrum of the protein in solution is compared with that of the protein adsorbed on Teflon and silica. Because of absorbance in the far UV by the aromatic styrene, it is impossible to obtain reliable CD spectra of proteins adsorbed on PS and PS- (EO)8. The CD spectrum of a protein reflects its composition of secondary structural elements (a -helices, / -sheets). The spectrum of dissolved a-chymotrypsin is indicative of a low content of or-helices and a high content of //-sheets. After adsorption at the silica surface, the CD spectrum is shifted, but the shift is much more pronounced when the protein was adsorbed at the Teflon surface. The shifts are in opposite directions for the hydrophobic and hydrophilic surfaces, respectively. The spectrum of the protein on the hydrophilic surface of silica indicates a decrease in ordered secondary structure, i.e., the polypeptide chain in the protein has an increased random structure and, hence, a larger conformational entropy. Adsorption on the hydrophobic Teflon surface induces the formation of ordered structural elements, notably an increase in the content of O -helices (cfi, the discussion in Sect. 3.1.4). 

Acknowledgements This work was supported by The Royal Society (UK) International Joint Project 2006/R2 Development of New Adsorbents for Blood and Plasma Purification and NATO Collaborative Linkage Grant SA(LST.CLG.978860) BioUsation of carbon adsorbent surface with ligand-induced conformers of human serum albumin. ... 

Cyt c is associated with the outer surface of the inner mitochondrial membrane. Phospholipids induce conformational changes in the protein and, in certain instances, the haem can convert to the high spin (S = 5/2) form, indicative of a weakening of the ligand field caused by displacement of the sixth ligand (Met-80). This has been associated with the detection of lipid radicals by direct EPR (at 11 K).65 Indeed, peroxidase-type activity is also evident in the reaction of cyt c with lipid hydroperoxides, as studied by spin trapping in conjunction with HPLC and MS.66... 

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