Absorption spectra indicate conformational alteration of myoglobin adsorbed on polydimethylsiloxane

Abstract

To assess the effects of adsorption on protein structure, ultraviolet optical absorption spectra of myoglobin (Mb) bound to polydimethylsiloxane (PDMS) were measured. A flow cell, which enabled adsorption under controlled hydrodynamic conditions, was used in conjunction with a conventional spectrophotometer to obtain the spectra. Adsorption to PDMS reduced significantly the absorbance in the Soret region of the Mb spectrum, whereas the spectrum in the region near 280 nm was essentially unaffected. This result showed that disruption of the native structure of Mb occurs following interaction with PDMS. Furthermore, the change in the absorption spectrum may indicate loss of heme from the heme pocket of the adsorbed protein. Mb structure was altered from its solution configuration within fifteen min of contact with the surface. Exchange of adsorbed Mb with Mb in solution had little or no effect on the absorption spectrum of the surface-confined protein, indicating that exchange occurs only between conformationally altered species or between native species.

Electrochemical behaviour of myoglobin at an array of microscopic liquid–liquid interfaces

“…UV/Vis absorbance spectroscopy can be used to investigate directly the effect of the environment on Mb tertiary structure because the absorbance spectrum of the haem group is directly affected by its physical environment [55]. Five different aqueous solutions were used in the preparation of sample solutions: purified H 2 O, 10 mM LiCl, 10 mM PBS, 10 mM HCl and 10 mM…”

“…However, in the higher pH solutions (no added acid), the Soret band remains unaffected. This is indicative of some denaturation/unfolding of the protein tertiary structure by the acidic aqueous phase electrolyte solution [55], although the extent of this process cannot be known from the UV/Vis spectra alone. The band due to the aromatic amino acids remains relatively unaffected in all aqueous solutions studied.…”

Structural and redox properties of mitochondrial cytochrome c co-sorbed with phosphate on hematite (α-Fe2O3) surfaces

“…However, because conformational changes ranging from relaxation of the heme pocket to a complete disruption of secondary and tertiary structure could account for the altered heme environment, optical absorption is not structurally specific [48].…”

One-step UV lithography for activation of inert hydrocarbon monolayers and preparation of protein micropatterns

“…Alternatively, methods such as microcontact printing allow one to create protein micropatterns over a large surface area by using microstructured polydimethylsiloxane (PDMS) stamps [9,10]. However, some studies show that contamination from stamps [11][12][13][14] and changes in chemical environments (humidity, and pH) during the protein transferring process may affect the integrity of the printed proteins [15][16][17].…”