The Rationalization of Carbon Monoxide and Hemoglobin Association

Abstract Carbon monoxide is a colorless, odorless, and poisonous gas, responsible for approximately 100,000 emergency room visits and over 420 deaths in the U.S. each year. Both carbon monoxide and oxygen bind to the ferrous ions in hemoglobin, but carbon monoxide has a significantly higher affinity. Extensive research has been conducted on the interaction between carbon monoxide and hemoglobin. However, a straightforward and practically applicable equation describing the relationship between carbon monoxide saturation and pressure is not found in the existing literature. In this paper, we establish an equation and confirm that the plot of CO saturation against CO pressure follows a hyperbolic shape, characterized by a continuous decrease in slope. In contrast, the oxygen-hemoglobin association curve is sigmoidal. These distinct curve shapes have different physiological implications. Our equation enables the determination of one variable—either saturation or pressure—if the other is known. Further analysis reveals the distribution of all five species of carboxyhemoglobin, showing that the triply bound form is abundant—a notable contrast to the distribution of oxyhemoglobin species. Additionally, our equation confirms that carbon monoxide’s affinity for hemoglobin is approximately 230 times higher than that of oxygen. Lastly, we propose a new general equation that may generate all carbon monoxide-hemoglobin association curves under various oxygen pressures. New and Noteworthy In this paper, we introduce the first known set of equations that model the Carbon Monoxide Hemoglobin association curve and the Carbon Monoxide Hemoglobin Fractional association curves. These novel equations represent a noteworthy advancement in the ability to quantitatively model CO binding to hemoglobin. We present the methodology utilized that explains the derivation of precise coefficients for these equations, along with the data points used to calculate the coefficients. Unlike existing models, our equations allow the direct computation of the CO saturation from the CO association equation and the CO fraction association equations from the partial pressure of carbon monoxide. This approach simplifies the mathematical modeling process while preserving a high degree of biological significance. Furthermore, the equations are built upon a complex and precise methodological foundation, enabling a deeper understanding of the binding behavior of hemoglobin in response to varying CO levels. This quantitative model has the potential to be applied to clinical practices in medicine. It provides insight into the complex relationship between CO and hemoglobin that is critical to many biological processes. Competing Interest Statement The authors have declared no competing interest. Footnotes Conflict of interest: none Funder: none Generative AI: During the preparation of this work, we used ChatGPT to edit English writing and grammar. After using ChatGPT, we reviewed and edited the content as needed and take full responsibility for the content of the publication.