Question

Most common secondary structure of protein Myosin in muscle and \(\alpha\)-keratin in hair are,

• A. both \(\alpha\)-helical
• B. \(\beta\)-pleated, \(\alpha\)-helical
• C. \(\alpha\)-helical, \(\beta\)-pleated
• D. both \(\beta\)-pleated

Hint:

Both are fibrous proteins whose chains coil into a right-handed helix held by hydrogen bonds.

Answer 1

The Correct Option is A

Step 1: Recall the examples
Typical alpha-helix proteins are keratin and myosin. Beta-pleated sheets are seen in silk fibroin.

Step 2: Compare the options
Options B, C and D each assign a beta-pleated sheet to at least one of the two proteins, which is wrong.

Step 3: Conclusion
Only option A has both proteins as $\alpha$-helical.

Final Answer:
Option A is correct. \[ \boxed{\text{(A) }\text{both }\alpha\text{-helical}} \]