The molecular insights into protein adsorption on hematite surface disclosed by in-situ ATR-FTIR/2D-COS study

Abstract

Proteins are of ubiquitous interest in the Life Sciences but are of interest in the Geosciences as well because of the significant role these compounds play in the biogeochemical cycling of trace and nutrient elements. Structural changes resulting from the adsorption of proteins onto mineral surfaces may alter protein biological function and other environmental interactions. Iron oxides are major sinks of a range of environmental elements including organic compounds. In this study, the adsorption of the broadly studied model protein BSA onto the hematite mineral surface was characterized as a function of pH, ionic strength, and BSA concentration using in-situ Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy. BSA lost the α-helix and gain β-sheets in the secondary structure during adsorption on hematite. BSA adsorption was maximum at pH 5, a value close to the BSA isoelectric point (~ pH 5), and lower at pH 4 and pH 7. Increasing ionic strength decreased to total BSA adsorption. Two-dimensional correlation spectroscopy analysis of the ATR-FTIR spectra revealed that higher initial BSA concentration and the consequent higher BSA surface loading enhanced BSA adsorption by protein–protein interaction, which less ordered structures changes into more compact forms decrease, hence compacting the structural arrangement and could promoting multilayers/aggregation formation on the mineral surface. The activity of enzymes following adsorption on mineral surfaces requires further study.

Analysis of micro- and nanoscale heterogeneities within environmentally relevant thin films containing biological components, oxyanions and minerals using AFM-PTIR spectroscopy

“…15 Furthermore, past studies have also shown BSA adsorption onto iron-containing mineral oxide surfaces from conformational changes, mainly via electrostatic interactions. 46–48…”

Characterization of Hydrophobic Interactions of SARS-CoV-2 and MERS-CoV Spike Protein Fusion Peptides Using Single Molecule Force Measurements

“…The conformational states adopted by oliopeptides and proteins at interfaces can be characterized ATR-FTIR (56)(57)(58)(59)(60)(61). In particular, the Amide I spectroscopic region (1600 -1700 cm -1 ), which arises from stretching vibrations of peptide carbonyl groups, is sensitive to the peptide conformational state (62-64).…”

Probing plasmon-induced surface reactions using two-dimensional correlation vibrational spectroscopy

“…27 Similarly, Barreto et al investigated the changes in the secondary structure of protein using in situ ATR/FTIR/2DCOS study. 28 It has been employed in studying the properties of the polymer and provides a way to characterize them. The 2DCOS spectra consist of synchronous ( φ ) and asynchronous correlation spectrum ( ψ ), where the synchronous spectrum consists of auto peaks along the diagonal positions and cross-peaks present at off-diagonal positions.…”