Peptide Sequence Homology
The degree of similarity between the amino acid sequences of two or more peptides, expressed as a percentage of identical or similar residues. High sequence homology between a therapeutic peptide and its endogenous counterpart suggests similar receptor interactions and biological activity.
Technical Context
Sequence homology is determined by aligning two peptide sequences and calculating the percentage of identical (or similar) amino acid positions. High homology to an endogenous peptide suggests the therapeutic analogue will interact with the same receptors and pathways. Lower homology indicates more extensive modification. Exenatide (from Gila monster exendin-4) shares approximately 53% sequence homology with human GLP-1, while liraglutide (a modified human GLP-1) shares approximately 97% homology. Homology also affects immunogenicity risk — peptides with lower homology to human sequences are more likely to be recognised as foreign by the immune system.