Silk fibroin contains predominantly β sheet conformation. Which of the following is true regarding its β sheets?

• A. Its antiparallel β sheets are oriented in the same direction.
• B. Its parallel β sheets are oriented in opposite directions.
• C. Its antiparallel β sheets are slightly more extended.
• D. Its parallel β sheets are slightly more extended.

Answer: (C)

Verified step by step guidance

1. Understand the structure of β sheets: β sheets are a type of secondary structure in proteins, characterized by their sheet-like arrangement of backbone strands. These strands can be oriented in parallel or antiparallel directions.
2. Differentiate between parallel and antiparallel β sheets: In parallel β sheets, the strands run in the same direction, while in antiparallel β sheets, the strands run in opposite directions.
3. Analyze the stability and extension of β sheets: Antiparallel β sheets are generally more stable due to optimal hydrogen bonding patterns, which can also lead to a slightly more extended conformation compared to parallel β sheets.
4. Consider the context of silk fibroin: Silk fibroin is known for its high content of β sheet structures, particularly antiparallel β sheets, which contribute to its strength and flexibility.
5. Conclude with the correct statement: Based on the properties of β sheets and the structure of silk fibroin, the statement 'Its antiparallel β sheets are slightly more extended' is true, reflecting the typical characteristics of antiparallel β sheets.