Tertiary Structure

The tertiary structure of a polypeptide involves is further coiling and folding to give a specific 3D structure due to covalent bonds such as disulfide bridges, ionic bonds and hydrogen bonds between the R-groups.Disulfide bridges are covalent bonds between -SH (sulfhydryl) groups in cysteine residues. The hydrogen atoms are removed by oxidation and the two sulfur atoms are joined by a -S-S- covalent bond.Ionic bonds form between carboxyl and amino groups in R-groups.Hydrogen bonds form between R-groups.The hydrophobic groups orient themselves away from the aqueous environment.