Alpha Helix Length Calculation
The length of an $\alpha$-helix depends on the number of amino acid residues and the distance between consecutive residues along the helix axis.
Key parameters for an $\alpha$-helix:
- Residues per turn: Approximately 3.6
- Rise per residue (distance along the axis): Approximately 1.5 Å (Angstroms)
Calculating Helix Length
To find the total length of the helix, multiply the number of residues by the rise per residue.
Given:
- Number of amino acid residues = 36
- Rise per residue = 1.5 Å
Calculation:
Length = (Number of residues) $\times$ (Rise per residue)
Length = 36 $\times$ 1.5 Å
Length = 54 Å
Therefore, the length of an $\alpha$-helix composed of 36 amino acid residues is 54 Å.
Important Questions from Protein Structure Folding Alpha Helix
- A 25 amino acid $\alpha$-helical protein is spanning the thickness of a mammalian cell membrane. Using the average dimensional parameters of a typical $\alpha$-helix, the thickness of the membrane will be ________ $\text{\AA}$ (rounded off to one decimal place).
The following diagram represents energy states of different protein folding steps, which includes-
1. Folded
2. Transition
3. Molten globule
4. Unfolded
Find the correct match of folding steps (1 to 4) with the energy state (P to S) in the diagram.- In a $\alpha$-helix, the R-groups on the amino acid residues
- Which one of the following pairs of amino-acids in the protein has high propensity to take up the $\alpha$-helix conformation?
- Which one of the following closely defines 'Molten Globule' state of a protein?
