MOTS-c (Mitochondrial Open Reading Frame of the Twelve S rRNA type-c) has rapidly become one of the most actively investigated peptides in metabolic and aging research. Since its discovery in 2015 by Lee et al. at the University of Southern California, the number of published MOTS-c studies has grown exponentially, driving increasing demand for high-quality, research-grade MOTS-c from European research institutions. This guide provides comprehensive information for researchers looking to source MOTS-c in the European market, covering quality specifications, supplier evaluation criteria, handling protocols, and regulatory considerations.
MOTS-c: Molecular Specifications
MOTS-c is a 16-amino acid peptide with the sequence MRWQEMGYIFYPRKLR. Key molecular specifications that should appear on any research-grade product:
Molecular formula: C107H152N26O25S2
Molecular weight: 2174.6 Da (monoisotopic mass: 2172.1 Da)
Appearance: White to off-white lyophilized powder
Solubility: Freely soluble in water and PBS up to 1 mg/mL. For higher concentrations, brief sonication may be needed.
Isoelectric point: Approximately pH 10.5 (basic peptide due to two arginine and one lysine residue)
The presence of methionine at position 1 and two internal methionine-adjacent residues makes MOTS-c susceptible to oxidation. This is a critical quality consideration, as methionine sulfoxide formation reduces biological activity. Properly handled and stored MOTS-c should show no evidence of oxidation on HPLC analysis.
Quality Standards: What to Verify in a COA
A comprehensive Certificate of Analysis for research-grade MOTS-c should include:
Purity by HPLC: Minimum 98% purity by reverse-phase HPLC with UV detection at 214 nm. The HPLC chromatogram should show a single dominant peak with baseline resolution from any impurity peaks. Trifluoroacetic acid (TFA) is the standard counter-ion; acetate salt is an alternative for cell culture applications where TFA interference is a concern.
Identity by Mass Spectrometry: Electrospray ionization mass spectrometry (ESI-MS) should confirm the expected molecular mass. Common charge states are [M+2H]2+ at m/z 1088.3 and [M+3H]3+ at m/z 725.9. Any deviation greater than 0.1% from theoretical mass indicates either sequence error or post-synthetic modification.
Amino Acid Analysis (AAA): Confirms the correct stoichiometric ratio of constituent amino acids. While not required for every lot, AAA provides an independent check on sequence fidelity.
Peptide Content: Lyophilized peptides contain a variable amount of non-peptide mass (water, counter-ions, salts). Peptide content, determined by nitrogen analysis or AAA, is typically 75-90% for TFA salt forms. A 10 mg vial with 80% peptide content contains 8 mg of actual peptide — this distinction matters for precise dosing calculations.
Endotoxin: For cell culture work, LAL testing should confirm endotoxin levels below 1 EU/mg. This is particularly important for MOTS-c given its use in metabolic cell biology research where endotoxin-activated inflammatory pathways would confound results.
Evaluating European MOTS-c Suppliers
Synthesis Quality
MOTS-c is manufactured by solid-phase peptide synthesis (SPPS) using Fmoc chemistry. The 16-residue sequence is moderately challenging due to the consecutive aromatic residues (Tyr-Ile-Phe-Tyr) and the methionine at position 1. Reliable synthesis requires optimized coupling protocols, real-time monitoring of coupling efficiency, and careful cleavage/deprotection conditions to avoid methionine oxidation and aspartimide formation.
Suppliers who manufacture their own peptides (or have direct, audited relationships with cGMP-certified synthesis facilities) can ensure consistent quality. Resellers who purchase from variable sources may deliver inconsistent lot-to-lot quality. Pepspan MOTS-c is sourced from a cGMP-certified peptide synthesis facility with full batch traceability.
Documentation and Transparency
Each production lot should have its own, unique COA with actual analytical data — not a template COA with only specification ranges. The COA should include the actual HPLC chromatogram image (or at minimum the retention time, peak area percentage, and gradient conditions), the MS spectrum with labeled peaks, and specific lot number matching the vial label.
EU-Based Logistics
Peptide stability during shipping is a practical concern. Lyophilized MOTS-c is reasonably stable at ambient temperature for short periods (days), but extended exposure to heat or humidity during transit from non-EU warehouses — especially with customs delays — can lead to moisture absorption and peptide degradation. EU-based shipping ensures delivery within 2-5 business days without customs processing, significantly reducing transit-related quality risks.
Reconstitution Protocol
Follow this protocol for reconstituting lyophilized MOTS-c:
Step 1: Allow the sealed vial to reach room temperature (15-20 minutes). This prevents condensation on the lyophilized powder when the vial is opened.
Step 2: Briefly centrifuge the vial (30 seconds at low speed) to ensure all powder is at the bottom.
Step 3: Add sterile water, PBS, or normal saline. For a 10 mg vial, adding 1 mL yields a 10 mg/mL stock solution (approximately 4.6 mM). For cell culture applications, use endotoxin-tested water.
Step 4: Allow the peptide to dissolve without agitation for 30 seconds, then gently swirl. Do not vortex vigorously. MOTS-c should dissolve within 1-2 minutes at room temperature.
Step 5: Verify the solution is clear and free of particulate matter.
Step 6: Prepare single-use aliquots. For in vivo mouse studies at 5 mg/kg using 25g mice, each injection requires 0.125 mg (12.5 microliters of 10 mg/mL stock). Aliquot accordingly to avoid repeated freeze-thaw.
Step 7: Snap-freeze aliquots in liquid nitrogen or dry ice and store at -20 degrees Celsius or below.
Storage Guidelines
Lyophilized (sealed vial): -20 degrees Celsius, stable for up to 24 months. Short-term storage at 4 degrees Celsius is acceptable for up to 3 months. Keep desiccated and protected from light.
Reconstituted stock solution: Store frozen aliquots at -20 degrees Celsius or below. Avoid more than 3 freeze-thaw cycles. Each cycle can degrade approximately 5-10% of peptide through aggregation and oxidation.
Working dilutions: Prepare fresh from stock on day of use. Dilute MOTS-c solutions at room temperature are stable for approximately 4-6 hours. At 4 degrees Celsius, working dilutions are stable for approximately 24-48 hours.
Published Dosing Protocols
For researchers designing MOTS-c experiments, published dosing data provides a starting framework:
In vivo (mouse, metabolic studies): 5 mg/kg/day IP injection (Lee et al., 2015, Cell Metabolism). Duration: 7-14 days for acute metabolic effects; 8-12 weeks for chronic studies.
In vivo (mouse, aging studies): 5 mg/kg/day IP injection for 2-4 weeks (Reynolds et al., 2021, Nature Communications). Treatment initiated at 23.5 months of age.
In vitro (cell culture): 1-10 micromolar in culture medium. For AMPK activation assays, effects are typically observed at 1-5 micromolar within 1-4 hours of treatment.
In vitro (osteoblast studies): 0.1-10 micromolar (Hu and Li, 2022). Effects on differentiation markers observed after 7-14 days of treatment.
Regulatory Status in Europe
MOTS-c sold as a research peptide in the EU is regulated as a laboratory chemical/research reagent. It is not classified as a pharmaceutical, controlled substance, or novel food when marketed exclusively for research purposes. Importation and purchase for bona fide scientific research is permitted across all EU/EEA member states without special permits.
Researchers should ensure their institutional purchasing and chemical handling procedures are followed. MOTS-c is not classified as hazardous under EU CLP Regulation and does not require special disposal procedures beyond standard peptide waste protocols.
Common Research Applications
Current published MOTS-c research spans multiple biological domains:
Metabolic studies: Glucose uptake, fatty acid oxidation, AMPK pathway characterization, insulin sensitivity modulation.
Aging research: Physical function in aged animals, mitochondrial function restoration, circulating MDP profiling.
Exercise biology: Exercise-mimetic effects, skeletal muscle metabolism, endurance and performance markers.
Bone metabolism: Osteoblast differentiation, osteoclast inhibition, Wnt/beta-catenin pathway regulation.
Mitochondrial biology: Mitonuclear communication, stress-responsive nuclear translocation, mitochondrial genome-derived signaling.
Beta-cell biology: Pancreatic beta-cell protection, lipotoxicity resistance, insulin secretion.
Why Choose Pepspan for MOTS-c Research
Pepspan MOTS-c 10mg is manufactured by cGMP-certified solid-phase peptide synthesis with the following specifications:
Purity: >98% by HPLC | Identity: Confirmed by ESI-MS | COA: Batch-specific, third-party verified | Packaging: Sealed vial under inert atmosphere | Shipping: EU-based, 2-5 business days | Free shipping on orders over 100 EUR.
Conclusion
As MOTS-c research continues to accelerate, having a reliable source of high-purity, well-characterized peptide is foundational to generating reproducible and publishable data. The specifications outlined in this guide — purity verification, identity confirmation, proper handling, and EU-based sourcing — represent the minimum standards for serious research use. By following the reconstitution and storage protocols described above and selecting a supplier with transparent quality documentation, researchers can ensure that their MOTS-c experiments reflect genuine biological effects rather than preparation artifacts.
All products are sold strictly for research purposes only. Not intended for human consumption or therapeutic use.