When two amino acids form a chemical bond between the C1 number one carbon position of one acid and the N2 number two nitrogen position of the other acid, an amide type of covalent chemical bond called a peptide bond is formed and links the two amino acids together. Polypeptides are subsequently linear chains of several amino acids linked together by such amide peptide bonds. Proteins are comprised of one or more large polypeptides that are typically more than fifty amino acids long 1.
- Biochemistry. 5th Edition. Berg JM, Tymoczko JL, Stryer L. New York: W H Freeman; 2002. Section 3.2 Primary Structure: Amino Acids Are Linked by Peptide Bonds to Form Polypeptide Chains [Link]