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When amino acid binds together by amide bonds, a large molecule is formed called peptide.Peptides are used as dietary supplements, to stimulate skin, and provide proteins required to the skin.

N-terminal amino acid are those amino acid which are free from amine group and C-terminal amino acid are those which are free from carboxyl group. N-terminal amino acid is written on the left end of the chain and C-terminal amino acid on the right.

a. The structure of Val-Glu peptide is drawn by joining adjacent $\mathrm{COOH}$and${\mathrm{NH}}_2$groups in amide bonds.

Structure of Val-Glu peptide

b. The structure of Gly-His-Leupeptide is drawn by joining adjacent and groups in amide bond

Structure of Gly-His-Leu peptide

c. The structure of M-A-T-T peptide is drawn by joining adjacent and groups in amide bonds.

Structure of M-A-T-T peptide