α-MSH (11-13) (free acid)

α-MSH (11-13) (free acid) is a synthetic peptide fragment derived from the C-terminal region of alpha-melanocyte-stimulating hormone, comprising the tripeptide sequence Lys-Pro-Val in its free acid form. As a minimal bioactive motif, this compound is of significant interest in peptide research due to its structural relationship to endogenous melanocortins and its potential to model specific receptor interactions. Its distinct biochemical properties and sequence context make it a valuable tool for investigating the structure-activity relationships within the melanocortin family, as well as for exploring the functional contributions of short peptide motifs in biological signaling pathways.

Peptide structure-activity studies: Researchers frequently employ α-MSH (11-13) (free acid) in systematic investigations of melanocortin receptor binding and activation. By isolating the C-terminal tripeptide, scientists can assess the minimal sequence requirements for receptor recognition, providing insights into how specific amino acid residues contribute to receptor selectivity and downstream signaling. Such studies are critical for deconvoluting the pharmacophore of melanocortin peptides and for guiding the rational design of novel ligands with tailored biological profiles.

Receptor binding assays: The tripeptide fragment serves as a reference ligand or competitive inhibitor in in vitro binding assays targeting melanocortin receptors, particularly MC1R, MC3R, MC4R, and MC5R. Its defined sequence allows for precise quantification of binding affinities and comparative evaluation alongside longer peptide analogs or modified derivatives. This application supports the characterization of receptor subtypes and the elucidation of ligand-receptor interaction dynamics in various experimental systems.

Peptide synthesis validation: As a well-characterized short peptide, α-MSH (11-13) (free acid) is routinely used as a standard in peptide synthesis and analytical laboratories. Its straightforward sequence and physicochemical properties make it suitable for method development, calibration of chromatographic systems, and quality control of peptide production workflows. Utilizing such standards ensures accuracy in peptide quantification and aids in troubleshooting synthetic protocols.

Functional motif mapping: The tripeptide motif represented by this compound is instrumental in mapping the functional domains of larger melanocortin peptides. By incorporating α-MSH (11-13) (free acid) into peptide libraries or chimeric constructs, researchers can dissect the contribution of terminal motifs to overall biological activity. This approach is particularly valuable for identifying key determinants of receptor activation, signal transduction, or peptide stability, thereby advancing the understanding of peptide-based signaling mechanisms.

Biochemical probe development: Owing to its defined sequence and manageable size, α-MSH (11-13) (free acid) is often adopted as a building block or probe in the development of labeled peptides, conjugates, or immobilized affinity reagents. These applications facilitate the study of peptide-protein interactions, enable the creation of targeted detection assays, and support the screening of novel modulators within the melanocortin system. The versatility of this tripeptide fragment enhances its utility across a range of biochemical and molecular biology research settings.

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