Give an example of a protein containing primarily alpha-helices. Is this a fibrous or globular protein?

Verified step by step guidance

1. Step 1: Understand the structure of alpha-helices. Alpha-helices are a common secondary structure in proteins, characterized by a coiled shape stabilized by hydrogen bonds between the backbone amide hydrogen and carbonyl oxygen atoms.
2. Step 2: Identify a protein that is known to contain primarily alpha-helices. A classic example is myoglobin, which is a protein that stores oxygen in muscle cells and is composed almost entirely of alpha-helices.
3. Step 3: Classify the protein as fibrous or globular. Proteins are categorized based on their overall shape and function. Fibrous proteins are elongated and structural, while globular proteins are compact and functional.
4. Step 4: Determine the classification of myoglobin. Myoglobin is a globular protein because it has a compact, spherical shape and is involved in a functional role (oxygen storage) rather than structural support.
5. Step 5: Summarize the findings. Myoglobin is an example of a protein containing primarily alpha-helices, and it is classified as a globular protein due to its compact shape and functional role.

Key Concepts

Alpha-Helices

Alpha-helices are a common structural motif in proteins, characterized by a right-handed coiled or spiral shape. They are stabilized by hydrogen bonds between the backbone amides of amino acids, typically every fourth residue. This structure contributes to the overall stability and functionality of proteins, influencing their interactions and roles in biological processes.

Fibrous vs. Globular Proteins

Proteins can be classified into two main categories: fibrous and globular. Fibrous proteins, such as collagen and keratin, have elongated structures and are typically involved in providing support and strength. In contrast, globular proteins, like enzymes and antibodies, are more spherical and often function in catalysis and regulation. The arrangement of secondary structures, including alpha-helices, plays a crucial role in determining a protein's classification.

Examples of Alpha-Helical Proteins

An example of a protein that contains primarily alpha-helices is alpha-keratin, found in hair, nails, and skin. This fibrous protein is composed of long chains of amino acids that form a helical structure, providing mechanical strength and resilience. Understanding the specific structure of such proteins helps in distinguishing their functional roles in biological systems.