Which of the following is not a fibrous protein?

Albumin

The correct answer is option 1. Albumin.

Fibrous proteins and globular proteins are two major categories of proteins based on their structure and function.

Fibrous proteins: These proteins have elongated, thread-like structures and are typically insoluble in water. They primarily serve structural and support functions. Examples include collagen, myosin, and keratin.

Globular proteins: These proteins have more compact, spherical shapes and are usually soluble in water. They often have dynamic roles, such as catalysis (enzymes), transport, and regulation. Examples include albumin, enzymes, and hemoglobin.

Analyzing the given options

1. Albumin:

Type: Globular protein.

Function: Found in blood plasma, albumin helps maintain osmotic pressure and transport substances like hormones, vitamins, and drugs.

Structure: Compact and soluble in water.

2. Collagen:

Type: Fibrous protein.

Function: Provides structural support and strength to connective tissues, skin, bone, tendons, and cartilage.

Structure: Long, rope-like fibers, insoluble in water.

3. Myosin:

Type: Fibrous protein.

Function: Plays a critical role in muscle contraction and motility.

Structure: Elongated structure with fibrous tails and globular heads, overall classified as fibrous due to its structural function.

4. Keratin:

Type: Fibrous protein.

Function: Provides mechanical strength and protection to hair, nails, feathers, and the outer layer of skin.

Structure: Long, fibrous strands, insoluble in water.

Conclusion: The protein that is not a fibrous protein among the given options is albumin. Therefore, the correct answer is: Albumin.