MCQ- Insertion of a protein into a liposome membrane

[TytoAlba95]

Homework Statement

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Relevant Equations

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Please give me clues as to how to solve this question.

The answer provided is (c).

 

[berkeman]

Homework Statement:: -
Relevant Equations:: -

View attachment 264821

Please give me clues as to how to solve this question.

The answer provided is (c).

You've been at the PF long enough to know that you have to show some effort. Since "Relevant Equations" doesn't apply to this type of question, how about you define all of the terms in this question? Then tell us your initial thoughts on how to figure this out...

 

[TytoAlba95]

I'm sorry to have broken the code, but it is true that I'm clueless. Okay...I'll still try writing something.
What could reconstitution mean in this context? A protein in a solution with liposomes trying to incorporate itself into their membrane?
Now that I know the correct option and if I think backwards, having the positive charge removed will be beneficial to incorporate the protein. Because lipid bilayer is not permeable to charged species, so a neutral C-terminal followed by a hydrophilic region will easily enter into the membrane.
Am I right?

 

[chemisttree]

Proteins are usually purified by precipitation followed by a dissolution step that is referred to as reconstitution. I think it implies not just solubility but a reconstitution of the protein’s 3 dimensional shape in solution.

 

[chemisttree]

I'm sorry to have broken the code, but it is true that I'm clueless. Okay...I'll still try writing something.
What could reconstitution mean in this context? A protein in a solution with liposomes trying to incorporate itself into their membrane?
Now that I know the correct option and if I think backwards, having the positive charge removed will be beneficial to incorporate the protein. Because lipid bilayer is not permeable to charged species, so a neutral C-terminal followed by a hydrophilic region will easily enter into the membrane.
Am I right?

I agree with your answer to a point. The generic schematic of the vesicle bilayer doesn’t allow us to make a sweeping generalization that substitution of a neutral endgroup for the positive endgroup would result in a better reconstitution (meaning a return of protein’s activity here). If we consider the bilayer is composed of DOPC, the most prevalent lipid bilayer component found in animal systems, you will notice the headgroup is positively charged.

And what do we know about like charges?