Question

Flavoproteins are usually intermediates in the transfer of electrons from NADPH to cytochrome P450 because A. NADPH cannot enter the membrane. B. flavoproteins can accept two electrons from NADPH and donate them one at a time to cytochrome P450. C. they have a more negative reduction potential than NADPH so accept electrons more readily. D. production of NADPH in the cytosol is the only source of electrons. E. they contain iron-sulfur centers.

Short answer

Answer: Flavoproteins can accept two electrons from NADPH and donate them one at a time to cytochrome P450.

Step-by-step solution

Analyze given options

To start solving this exercise, we first need to evaluate each of the given options (A-E) and determine which one accurately describes the role of flavoproteins in the electron transfer process.

Evaluate option A

First, we look at option A: "NADPH cannot enter the membrane". This statement is not specific about the role of flavoproteins and is not a valid reason for flavoproteins being intermediates in the electron transfer process, so we can discard this option.

Evaluate option B

Next, we examine option B: "flavoproteins can accept two electrons from NADPH and donate them one at a time to cytochrome P450". This statement demonstrates the specific role of flavoproteins in the electron transfer process involving NADPH and cytochrome P450. This option seems promising, but we need to consider the remaining options as well.

Evaluate option C

Moving to option C: "they have a more negative reduction potential than NADPH so accept electrons more readily". This option does not accurately describe the role of flavoproteins because their reduction potential does not explain why they act as intermediaries between NADPH and cytochrome P450. So, we can discard this option.

Evaluate option D

Now, we evaluate option D: "production of NADPH in the cytosol is the only source of electrons". This statement is not specifically about the role of flavoproteins, so we can discard this option as well.

Evaluate option E

Lastly, we examine option E: "they contain iron-sulfur centers". Although flavoproteins may contain iron-sulfur centers, this statement does not describe why they are intermediates in the electron transfer process between NADPH and cytochrome P450. So, we can rule out this option as well.

Determine the correct option

After examining all the options, we conclude that the correct statement is option B: "flavoproteins can accept two electrons from NADPH and donate them one at a time to cytochrome P450". This explanation highlights the role of flavoproteins in the electron transfer process between NADPH and cytochrome P450.