These questions require around a paragraph or two for the answer. For full ratin

Question

These questions require around a paragraph or two for the answer. For full rating, answer in such manner please.

1) What predictions can you make about the primary structure of an alpha-helical region of a protein that spans a biological membrane?

2) Cells tend to have about ten-fold more Na+ on the outside relative to the inside, whereas the situation with K+ ions is the opposite.  How can this happen since the collapse of these gradients would be energetically favored?  Is there a biochemical benefit to having these ion gradients?

Explanation / Answer

Alpha helix is stabilized by hydrogen bonds. There are psi and phi values that faill in the allowed regions f ramanchandran diagram. The ramachandran diagram indicates allowed conformations of polypeptides and only three small regions show values that are allowed. Alpha helix has amino acids that have side chains that are outward so they don't react wtih polypeptide backbone. The helix is stablized by hydrogen bonds between NH from the peptide linkage and the electronegative carbonyl oxygen atom of teh 4th amino acid. There are some other interactions that stablize the alpha helix such as ionic interactions between amino acids and these are very important because interactions between amino acids can destabilize or stablize the alpha helix. For example: the negatively charged glutamic acid, the carboxyl groups repel each other so much that they can't form an alpha helix. In alpha helix, the hydrophobhic residues appear at 1st and 2nd helices of a coiled to form form buried hydrophobic interactoiins Three sodium ions bind to protein channel and ATP provides energy that changes the shape of the channel. One phosphate group remains bound to the channel when sodium is going to the outside of teh cell. When sodium is released the new shape of the channel has a high affinity for potassium ions and two potassium ions bind and that changes the shape of the channel which then releases the potassium ions and reverts to its original shape.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.