Answer:
keratin.
Explanation:
Proteins are made of the polymers of the alpha amino acids that are linked together through the peptide bond. Important proteins present in human body are keratin, collagen and mucin.
Keratin is the important protein present in nails, hairs and outer layer of skin. This protein helps in the protection of the epithelial cells and insoluble in water. Keratin protein is responsible for the reduction of excess water loss at the skin surface.
Thus, the answer is keratin.
