Question

When exposed to carbon monoxide, the base pigment of Cytochrome P enzymes absorb light at:

• A. 450 nm
• B. 370 nm
• C. 254 nm
• D. 600 nm

Answer 1

The Correct Option is A

Cytochrome P450 enzymes, often referred to as CYPs, are a family of enzymes containing heme as a cofactor, which are important for the oxidation of organic substances. When these enzymes are exposed to carbon monoxide, they undergo a specific change in their absorption spectrum.

The question asks about the light absorption characteristics of Cytochrome P450 enzymes when exposed to carbon monoxide. Here's the explanation:

1. Cytochrome P450 Enzymes: These are heme-thiolate proteins, and their characteristic feature is the formation of a complex with carbon monoxide.
2. Absorption Characteristics: In their reduced state, when cytochrome P450 is bound with carbon monoxide, the complex displays a characteristic absorption peak in the ultraviolet-visible spectrum.
3. Soret Peak: The Soret peak is a common feature in heme proteins. For Cytochrome P450, when it binds with carbon monoxide, the Soret band shifts and has a strong absorbance around 450 nm.
4. Correct Answer: Therefore, when Cytochrome P enzymes are exposed to carbon monoxide, they absorb light maximally at approximately 450 nm.

Conclusion: The correct option is 450 nm which corresponds to the characteristic peak absorption of the Cytochrome P450-Carbon monoxide complex, known as the cytochrome P450 signature peak. Other options (370 nm, 254 nm, and 600 nm) fall outside this specific absorption characteristic for this enzyme complex.