SS-31

SS-31 is a linear 4-residue peptide containing alternating aromatic-cationic residues (D-Arg / 2,6-dimethyltyrosine / Lys / Phe-amide) that together produce a polycationic amphipathic structure documented in the literature for selective accumulation in the mitochondrial inner membrane. The molecule's interaction profile in published work centers on cardiolipin binding — a unique mitochondrial-inner-membrane phospholipid — with downstream investigations of cytochrome-c stabilization, electron-transport-chain efficiency, and ATP-synthesis-pathway research. Pharmacokinetic descriptors documented in published animal-model investigations include rapid cellular uptake driven by the cationic charge, with mitochondrial-compartment accumulation reported across cell-culture and tissue-distribution studies. Interaction profile in the literature spans cardiolipin-protein-complex stabilization, reactive-oxygen-species-pathway research, and mitochondrial-bioenergetics investigations. All activity descriptors here are framed as documented in published research.

Experimental domains documented in the published literature include cardiolipin-binding biochemistry assays, mitochondrial-membrane-targeting studies in cell-culture systems, electron-transport-chain efficiency investigations, cytochrome-c-stabilization research in isolated mitochondrial preparations, oxidative-stress-pathway studies, ATP-synthesis-pathway research, structure-activity work probing the role of the alternating aromatic-cationic motif in mitochondrial targeting, and comparative work alongside other mitochondria-targeted research peptide scaffolds (MitoQ, related SS-class peptides). Investigators have also characterized SS-31 in studies of mitochondrial-permeability-transition-pore research and in screening assays for mitochondria-targeted peptide-conjugate development. Use in laboratory research extends to mechanism-elucidation paradigms where the tetrapeptide serves as a defined mitochondria-targeted reference. The reference standard is supplied for these and equivalent in-vitro and animal-model experimental contexts only, with no associated guidance for human, clinical, or veterinary application.

Each lot is characterized by reverse-phase HPLC for chromatographic purity and by mass spectrometry for molecular-ion confirmation against the C32H49N9O5 empirical formula. Purity is reported as an HPLC-area percentage on the Certificate of Analysis distributed with every lot, alongside the molecular-weight match within instrument tolerance. The non-canonical 2,6-dimethyltyrosine residue and D-amino-acid stereochemistry are confirmed by tandem mass spectrometry when included in the lot's release specification — important parameters given the molecule's reliance on the alternating aromatic-cationic motif for mitochondrial targeting. Peptide content where applicable is determined by amino-acid analysis following the analytical method specified on the COA. Residual solvent and water content are reported categorically when these parameters are part of the lot's release specification. The COA records the lot identifier, manufacturing date, and analytical method versions used.

For laboratory storage, the lyophilized reference standard should be held at −20°C in its sealed, light-protected container until ready for analytical use. Allow vials to equilibrate to ambient temperature before opening to avoid moisture condensation on the lyophile. Reconstitution for in-vitro experimental use is typically performed in bacteriostatic water or a researcher-selected buffer compatible with the downstream mitochondrial-assay or cell-culture-treatment system; once reconstituted, store the working solution at 2–8°C and characterize stability in the relevant buffer prior to extended storage. The cationic peptide may bind to anionic glassware or plastic surfaces — assay-specific recovery characterization is recommended in low-binding labware. Avoid repeated freeze-thaw cycles of reconstituted material. These handling parameters reflect general best-practice for cationic mitochondria-targeted peptide reference standards and do not constitute preparation guidance for human or veterinary application.