Product Identity and Physical Properties
Leupeptin, identified by CAS 103476-89-7 and IUPAC name Leupeptin, is commonly supplied as the hemisulfate salt. Key synonyms include Leupeptin hemisulfate salt, Acetyl-Leu-Leu-Arg-al, and N-Acetyl-L-leucyl-L-leucyl-L-argininal hemisulfate salt. This compound is a white to off-white powder with a characteristic profile suited for biochemical applications.
Grade Specifications and Quality Parameters
The ≥85% (HPLC) grade of Leupeptin is designed for research and analytical applications where high purity is essential for reproducible results. This grade ensures minimal interference from related peptide impurities during protease inhibition assays and protein characterization studies.
| Parameter | Leupeptin (This Grade) | Typical Research Grade | Typical USP Grade |
|---|---|---|---|
| Assay (HPLC) | ≥85% | ≥80% | ≥95% (when applicable) |
| Physical Form | Powder | Powder or solution | Defined crystalline |
| Quality Level | Not specified | Variable | Pharmacopoeial |
| Impurity Profile | Not specified | Variable | Controlled per USP |
| Solubility (H₂O) | 50 mg/mL | Variable | Defined per monograph |
The ≥85% (HPLC) specification indicates that at least 85% of the material is the active Leupeptin peptide, with the remainder comprising water, counterion (hemisulfate), and minor peptide-related impurities. This purity level is adequate for most biochemical inhibition studies and protein work where absolute pharmacopoeial compliance is not required.
Handling, Storage, and Safety
Leupeptin is classified under Storage Class 1 and carries a Water Hazard Class (WGK) of 3, indicating a significant potential for water pollution. The GHS signal word and hazard codes are not specified in the source data; therefore, users must consult the provided Safety Data Sheet (SDS) for complete hazard information. No flash point data is available for this compound.
Storage recommendations include keeping the powder in a tightly sealed container, protected from moisture and light, at recommended temperatures (typically -20°C to 8°C for long-term stability). Standard laboratory PPE — including gloves, safety glasses, and a lab coat — should be worn during handling. Avoid inhalation of dust and contact with skin or eyes.
Solubility and Solution Preparation
Leupeptin demonstrates excellent aqueous solubility, with a specified limit of H₂O: 50 mg/mL. For analytical applications, water is the primary recommended solvent. Solutions can be prepared by dissolving the powder in deionized or distilled water with gentle agitation, avoiding excessive heat that may degrade the peptide.
For cell lysis buffers and immunoprecipitation workflows, Leupeptin is typically added at effective concentrations of 10–100 μM. Solutions should be prepared fresh or aliquoted and stored at -20°C to minimize freeze-thaw cycles. Avoid prolonged storage in aqueous solution at room temperature, as proteolytic activity may degrade the inhibitor over time.
Applications in Analytical and Research Settings
Leupeptin is a broad-spectrum inhibitor of serine and cysteine proteases, specifically inhibiting plasmin, trypsin, papain, calpain, and cathepsin B. It does not inhibit pepsin, cathepsins A and D, thrombin, or α-chymotrypsin. Biochemically, Leupeptin helps protect motoneurons from apoptosis and enhances muscle function following nerve injury, exhibiting neurotrophic and growth-stimulating actions.
In laboratory practice, Leupeptin is used in ice-cold lysis buffer to harvest cells for western immunoblotting and immunoprecipitation. It is also incorporated into chromatin immunoprecipitation (ChIP) lysis buffer for isolating fragmented chromatin samples, and in lysis buffer I for tandem affinity purification (TAP). The powder form (≥85% HPLC) is suitable for preparing stock solutions for HPLC, GC, and NMR applications, though the compound is most commonly employed in biochemical assays rather than analytical chromatography.
Supplier Selection Guide
Research quantities of Leupeptin (CAS 103476-89-7) are available from major suppliers. For bulk production, formal quotations with CoA, SDS, and lead time are available within 24 hours — contact our team to inquire about current pricing and discuss your requirements.
A: Leupeptin is a protease inhibitor used to prevent proteolysis during protein extraction, western blotting, immunoprecipitation, and chromatin immunoprecipitation (ChIP) assays. It inhibits serine and cysteine proteases including trypsin, papain, calpain, and cathepsin B.
A: It indicates that the material contains at least 85% active Leupeptin as determined by high-performance liquid chromatography. The remainder consists of water, hemisulfate counterion, and minor peptide-related impurities, which is acceptable for most biochemical research applications.
A: Store the powder in a tightly sealed container, protected from moisture and light, typically at -20°C. Aqueous solutions should be aliquoted and stored frozen, avoiding repeated freeze-thaw cycles. Storage Class 1 and WGK 3 classifications apply.
A: HPLC is the primary method for purity determination, as specified by the ≥85% (HPLC) grade. Additional methods such as mass spectrometry or amino acid analysis can confirm identity. The compound is also suitable for NMR analysis in D₂O or aqueous solvents.
A: Standard documentation includes a Certificate of Analysis (CoA) detailing the HPLC purity result and batch-specific data, along with a Safety Data Sheet (SDS) covering handling, storage, and hazard information. Additional documentation may be available upon request.
Leupeptin (CAS 103476-89-7)
Grade: ≥85% (HPLC), powder
Applications: Protease inhibitor for biochemical research, protein extraction, and cell lysis buffers
