CO₂-Formatics: How Do Proteins Bind Carbon Dioxide?

Abstract

The rising atmospheric concentration of CO2 has motivated researchers to seek routes for improved utilization, increased mitigation, and enhanced sequestration of this greenhouse gas. Through a combination of bioinformatics, molecular modeling, and first-principles quantum mechanics the binding of carbon dioxide to proteins is analyzed. It is concluded that acid/base interactions are the principal chemical force by which CO2 is bound inside proteins. With respect to regular secondary structural elements, β-sheets show a marked preference for CO2 binding compared to α-helices. The data also support the inference that while either or both oxygens of CO2 are generally tightly bound in the protein environment, the carbon is much less “sequestered.” First principles and more approximate modeling techniques are assessed for quantifying CO2 binding thermodynamics.

CO2 capture using whey protein isolate

“…It can be noticed that the amount of ␤-sheets in the protein structure increases as the spray drying temperature increases from 130 • C (peak area = 0.03898) to 170 • C (peak area = 0.04016) compared with the commercial WPI powders (peak area = 0.02862). This trend can be correlated with the amount of carbon dioxide adsorbed on the protein surfaces based on a previous computational study [22]. The hydrogen bonds between the oxygen sites on the carbon dioxide and the motifs on the side chains of the amino acids are the main areas for the carbon dioxide adsorption process [22].…”

“…This trend can be correlated with the amount of carbon dioxide adsorbed on the protein surfaces based on a previous computational study [22]. The hydrogen bonds between the oxygen sites on the carbon dioxide and the motifs on the side chains of the amino acids are the main areas for the carbon dioxide adsorption process [22]. The ␤-sheet is preferred for the protein-carbon dioxide interaction rather than the ␣-helix, because the ␤-sheet has less intermolecular hydrogen bonds, which results in a less stable secondary structure than the ␣-helix [58].…”

“…In 2009, in a computational chemistry simulation study of protein structure and interaction with CO 2 using molecular mechanics through density functional tight binding (DFTB) and density functional theory (DFT), Cundari et al [22] concluded that the ␤-sheets are more amenable to CO 2 binding than ␣-helices. The acid-base interactions influence the binding of CO 2 to protein by changing the electronegativities of proteins [22], which was suggested to be more significant than hydrophobicity.…”

“…The acid-base interactions influence the binding of CO 2 to protein by changing the electronegativities of proteins [22], which was suggested to be more significant than hydrophobicity. Hence, the oxygen in the CO 2 molecule bonded with the protein more tightly than the carbon as a result of the negative charge on the oxygen ion [22].…”

“…The acid-base interactions influence the binding of CO 2 to protein by changing the electronegativities of proteins [22], which was suggested to be more significant than hydrophobicity. Hence, the oxygen in the CO 2 molecule bonded with the protein more tightly than the carbon as a result of the negative charge on the oxygen ion [22]. Nevertheless, there is still a gap in terms of using this knowledge of the critical binding sites to establish which kind of proteins are most promising for CO 2 capture, and also this computational result requires confirmation from experiments.…”