Mini-review Paper

Mini-review Paper

Introduction

“Reduction Potentials of P450 Compounds I and II: Insight into the Thermodynamics of C–H Bond Activation” by Mittra and Green is a significant article as it describes redox potentials and bond strengths that describes the activation of thermodynamics of C-H bonding in cytochrome P450 catalysis. The authors perform redox titrations using [Ir(IV)Cl₆] ²⁻, which enables them to determine the strength of Fe(IV)OH/Fe(III)OH₂) bond in CYP158 (Mittra and Green 5505). The article concludes that P450s influences the oxygenation of hydrocarbons. Besides, these enzymes influence the cleaving reactions of the carbon-carbon bond. Also, the study illustrates that P450s supports the synthesis of ethyl carbamate that produces vinyl carbonate. Again, the authors reveal that P450s trigger the reduction of testosterone to yield 17β-hydroxy-4 (Mittra and Green 5507). Finally, the article shows that P450 enzymes break down C_n fatty acids; thereby, releasing the f C_n−1 alkenes. The authors use the restricted open-shell (ROS), reduction titrations, and semi-empirical ROS techniques during the research. These methods are suitable as they improve the accuracy of research outcomes. For example, they help the researchers determine the reduction potential of P450-I and the strength of the P450-II bond (Mittra and Green 5504). Overall, this is a critical article in chemical biology as it explores the impacts of P450 compounds on C-H bonds.

Background

The article addresses various chemical biology questions: What role does the C-H bond activation has in the catalysis of cytochrome P450? What are the redox potentials and bond strengths ideal for the thermodynamics of the C-H bond in P450 catalysis? These questions are crucial in this study as they help the researchers determine the role of P450 enzymes.

Researchers have performed extensive research on the uses of P450s in chemical processes. According to Hartwig and Larsen, P450s are crucial fusion proteins as they catalyze fatty acids reactions; henceforth, they are ideal for use in synthetic procedures (287). Also, Krest et al. reveal that P450s compounds catalyze the activation of the C-H bonds as they are thiolate-ligated (696). Besides, P450s are critical fusion proteins as, during the activation of the C-H bonds, they increase the reactivity of the I compound, which supports electron-donation processes (Onderko et al. 624). Again, Yosca et al. show that P450s trigger the oxidation of substrate C-H bonds as they activate oxygen in iron compounds (826). Overall, the unique nature of P450s makes it suitable for use in chemical reactions.

Key Experiments

The researchers performed a mixed experiment using potassium hexachloroiridate (IV) extracted from Sigma Aldrich. They applied CYP158 in BL21 cells. The analysis uses proteins with R_z ≥ 2 to improve the validity of the research results. The researchers used the SFM-400 scan spectrometer to monitor spectral changes. Besides, a TIDAS photodiode helps gather absorption data (Mittra and Green 5508).  Also, the article uses extinction coefficients to assess the chemical concentration levels. Likewise, the ROS calculations help determine the reactivity of SeCYP119-I towards the C-H bond. These techniques enhance the reliability of the study.

Quality control measures make the article valuable for use in research. Primarily, the researchers performed the experiments at a temperature of 7 ⁰C. This measure is suitable as it creates a conducive temperature that favor the operations of enzymes. Also, the researchers used the SFM-400 technique to scan spectral changes. These control measures promote the legitimacy of this research. However, adding a solution of 2.5 mM K₂IrCl₆ in Nano pure water is a negative control measure as it affects the _PH level of the stock solution.

Reflection 

The paper has various shortcomings that limit its application in scientific research. Chiefly, the article does not explain the reaction of P450 under high temperatures. Besides, the study does not provide answers to factors that limit the functionality of P450 compounds. If it were my project, I would develop a control experiment to assess factors that affect the performance of P450s under varying conditions.

Works Cited

Hartwig, John F., and Matthew A. Larsen. “Undirected, Homogeneous C−H Bond Functionalization: Challenges and Opportunities.” ACS Cent. Sci. 2016, 2, 281.

Krest, Courtney M., et al. “Significantly Shorter Fe–S Bond in Cytochrome P450-I is Consistent with Greater Reactivity Relative to Chloroperoxidase.” Nature Chemistry, vol. 7, no. 9, 2015, pp. 696-702.

Mittra, Kaustuv, and Michael T. Green. “Reduction Potentials of P450 Compounds I and II: Insight into the Thermodynamics of C–H Bond Activation.” Journal of the American Chemical Society, vol. 141, no. 13, 2019, pp. 5504-5510.

Onderko, Elizabeth L., et al. “Characterization of a Selenocysteine-ligated P450 Compound I Reveals Direct Link Between Electron Donation and Reactivity.” Nature Chemistry, vol. 9, no. 7, 2017, pp. 623-628.

Yosca, T. H., et al. “Iron(IV)hydroxide pKa and the Role of Thiolate Ligation in C-H Bond Activation by Cytochrome P450.” Science, vol. 342, no. 6160, 2013, pp. 825-829.