For each of the following proteins, note whether the main secondary structure feature is α helix, β-pleated sheet, or both.
a. collagen

Verified step by step guidance

1. Understand the concept of secondary structures in proteins: Proteins have secondary structures that are stabilized by hydrogen bonding. The two main types are α helix (a coiled structure) and β-pleated sheet (a sheet-like structure).
2. Recall the structure of collagen: Collagen is a structural protein found in connective tissues such as skin, tendons, and bones. It has a unique triple-helix structure, which is a variation of the α helix.
3. Identify the dominant secondary structure in collagen: Collagen's triple-helix structure is primarily based on the α helix, but it is not a standard α helix. Instead, it is a specialized form adapted for its structural role.
4. Note that β-pleated sheets are not a feature of collagen: Collagen does not contain β-pleated sheets as part of its secondary structure.
5. Conclude that the main secondary structure feature of collagen is the α helix, specifically in the form of a triple helix.

Key Concepts

Secondary Structure of Proteins

The secondary structure of proteins refers to the local folded structures that form within a polypeptide due to hydrogen bonding between backbone atoms. The two most common types are α helices, which are coiled structures, and β-pleated sheets, which are formed by parallel or antiparallel strands. Understanding these structures is crucial for analyzing protein function and stability.

Collagen Structure

Collagen is a structural protein that primarily consists of a unique triple helix formation, which is a type of α helix. This structure provides tensile strength and is a major component of connective tissues. While collagen does not typically form β-pleated sheets, its unique helical structure is essential for its biological function.

Protein Folding and Function

The folding of proteins into specific secondary structures is critical for their overall three-dimensional shape and function. The arrangement of α helices and β-pleated sheets influences how proteins interact with other molecules and perform their biological roles. Understanding these relationships helps in fields like biochemistry and molecular biology.