Surface-induced conformational changes

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. 

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... 

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... 

Schematic representation of the change in conformation of the hexokinase enzyme on binding substrate. E and E are the inactive and active conformations of the enzyme, respectively. G is the sugar substrate. Regions of protein or substrate surface excluded from contact with solvent are indicated by a crinkled line. Figure 8.3 presents a more detailed view of the hexokinase molecule. (Source From W. S. Bennett and T. A. Steitz, Glucose-induced conformational changes in yeast hexokinase, Proc. Natl. Acad. Sci. USA 75 4848, 1978.)...

The arrangement of the proteins within the membrane seems to depend to some extent on the electrostatic surface potential and interface permittivity. It is influenced by electrostatic interaction between the proteins, polar head groups of the phospholipid and ions within the aqueous medium of the membrane surface. This can be affected by exogenous molecules such as drugs. Phospholipid-induced conformational change in intestinal calcium-binding protein in the absence and presence of Ca2+ has been described [37]. There is, however, no doubt that hydrophobic interactions between peptides and membrane interfaces play an important role. A general frame-... 

Mechanosensing is postulated to involve many different cellular and extracellular components. Mechanical forces cause direct stretching of protein-cell surface integrin binding sites that occur on all eukaryotic cells. Stress-induced conformational changes in the extracellular matrix may alter integrin structure and lead to activation of several secondary messenger pathways within the cell. Activation of these pathways leads to altered reg-... 

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