Alpha-keratin is a type of protein that forms a key structural component in the hair, nails, and skin of mammals. It is a fibrous protein that provides strength and resilience, helping to protect these tissues from damage. Alpha-keratin is characterized by its helical structure, which allows it to be flexible yet durable. This protein is found in various forms across different species, contributing to the unique characteristics of their hair and skin. For example, the wool of sheep is primarily made of alpha-keratin, which gives it its softness and warmth. Overall, alpha-keratin plays a crucial role in maintaining the integrity of many biological structures.