Final answer:
The modified amino acid residue is likely derived from proline, becoming hydroxyproline post translational modification. This demonstrates the diverse capabilities of amino acids in proteins to undergo modifications that impact their stability and function, as seen in the structure of collagen and biological fitness influences.
Step-by-step explanation:
The modified amino acid residue described is likely derived from proline, which can be hydroxylated after its incorporation into a protein, forming hydroxyproline. This type of post-translational modification can improve the structural stability of proteins, such as collagen, where hydroxyproline plays an essential role. The process emphasizes how amino acid modifications can directly influence the function and biological fitness of a protein.
Further post-translational modifications may include the enzymatic removal of certain N-terminal amino acids, such as the N-formyl methionine in prokaryotes or methionine in eukaryotes. It's also common for proteins in eukaryotic cells to have the amino group of the amino terminal residue acetylated. Additionally, selenocysteine is often recognized as the 21st amino acid, known for being incorporated into proteins by a unique biosynthesis pathway and recognized for its role in enhancing biological fitness.
Other examples of modified amino acids include the replacement of certain functional groups with others. For instance, the carboxyl group in norepinephrine can be replaced with a benzene ring contributing to its function as a neurotransmitter.