Dominant secondary structure element in myoglobin and hemoglobin: which motif predominates?

Introduction:
Protein secondary structure comprises repeating motifs like α-helices and β-sheets. Globins (myoglobin and hemoglobin) are classic α-helical proteins.

Given Data / Assumptions:

• Considering globin fold proteins.
• Myoglobin and hemoglobin share a conserved fold composed largely of helices A–H.

Concept / Approach:

The globin fold is dominated by α-helices connected by short loops; β-structure is minimal to absent.

Step-by-Step Solution:

Verification / Alternative check:

Crystal structures and secondary-structure assignments (e.g., DSSP) show majority α-helix content in globins.

Why Other Options Are Wrong:

β-strands and β-turns are present in many proteins but not dominant in globins; “All equally” is incorrect; collagen triple helix is not present in globins.

Common Pitfalls:

Assuming all proteins contain balanced α and β content.

Final Answer:

α-helix (alpha helix)