Protein Structure Levels

[MedPR]

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Due to the ring structure of proline, it cannot conform to the geometry of the a-helix and creates a bend in the peptide chain. This phenomenon assists in the creation of what level of protein structure?

A. Secondary
B. Tertiary

So, primary = AA sequence, secondary = a-helix, b-sheet, tertiary = folded.

If something creates a bend in the chain, doesn't that contribute to the secondary structure and then maybe to the tertiary structure?

 

[Erythropoietin]

Due to the ring structure of proline, it cannot conform to the geometry of the a-helix and creates a bend in the peptide chain. This phenomenon assists in the creation of what level of protein structure?

A. Secondary
B. Tertiary

So, primary = AA sequence, secondary = a-helix, b-sheet, tertiary = folded.

If something creates a bend in the chain, doesn't that contribute to the secondary structure and then maybe to the tertiary structure?

bending affects the 3D structure, which is the tertiary structure

 

[MedPR]

bending affects the 3D structure, which is the tertiary structure

So every a-helix and b-sheet are exactly the same, regardless of the primary structure?

 

[MT Headed]

So every a-helix and b-sheet are exactly the same, regardless of the primary structure?

Yes. Sheets and helicies are formed by interactions amongst the peptide backbone, that continuous chain of CH-NH-CO-CH-NH-CO... found in the a chain of any amino acids.

Technically proline is an imino acid, and including one adds nonstandard atom patterns to the backbone, which disrupts whatever chain or helix you were building.

 

[MT Headed]

So every a-helix and b-sheet are exactly the same, regardless of the primary structure?

There are some cases where you could construct amino acid patterns that put hydrophobic and hydrophillic side groups together, or a lot of positively charged groups together, or even a bunch of huge groups like Trp together that would also disrupt the secondary structure, but the important point here is that the R groups do not participate in the bonding that stabilizes sheets and helicies.