Some organisms use uncommon amino acids in synthesizing specialized proteins. Homoserine and homocysteine (pictured) are used in metabolism as intermediates in the production of common amino acids. Some scientists believe that homoserine and homocysteine could be used in proteins. Which of these could function as an amino acid in proteins? Neither homoserine nor homocysteine could be used in proteins because they both have an extra carbon unit in the side chain.
Only homoserine can be used in protein production because homocysteine contains a sulfur atom, which cannot be a part of proteins.
Only homocysteine can be used in protein production because homoserine contains an extra hydroxyl group, which will denature the protein.
Both homoserine and homocysteine could be used in protein production because they contain both the amine group and carboxylic acid required for peptide bonds.