Final answer:
In biology, N-ends can be modified through mechanisms such as N-terminal acetylation, glycosylation, cyclization, and substitution or deletion of amino acids. These modifications can enhance protein stability, function, and resistance to degradation.
Step-by-step explanation:
In biology, N-ends can be modified through various mechanisms to enhance protein stability and function. One common modification is N-terminal acetylation, where the amino group of the N-terminal residue is acetylated. This modification occurs in about 50% of eukaryotic proteins and can affect protein folding, stability, and interactions.
Glycosylation is another modification that can occur at N-ends, where carbohydrate chains are added to the protein. This modification, particularly N-linked protein glycosylation, can increase plasma stability and resistance to degradation by exopeptidases. It involves the attachment of carbohydrate chains to specific Asn residues in glycoproteins.
Furthermore, N-ends can also undergo cyclization through disulfide bonds, lanthionine, dicarba, hydrazine, or lactam bridges. This cyclization can decrease conformational flexibility and increase stability against proteolysis. Additionally, substitution of natural amino acids with unnatural analogues or deletion of specific amino acids can modify N-ends for enhanced stability and target affinity.