Merck, 11359053001, Pepstatin

General description
Isovaleryl-L-val-L-val-statyl-L-alanyl-statin (Isovaleryl-L-val-L-val-4-(S)-amino-3-(S)-hydroxy-6-methyl-heptanoyl-2-ala-4-(S)-amino-3-(S)-hydroxy-6-methyl-heptanoic acid)
Pepstatin is a low molecular weight, highly specific inhibitor of acid proteases (in particular aspartate proteases).
Application
Pepstatin is used for the protection of proteins and enzymes during isolation and purification procedures. It facilitates the investigation of enzyme mechanisms and biological function, and the classification of proteases. Pepstatin is applied in affinity chromatography, structural and pharmacological research, in HIV research (inhibition of retroviral-coded proteases, e.g., HIV-1), and cancer research (as an immunostimulant and anti-tumor drug).
Biochem/physiol Actions
Pepstatin A is an inhibitor of acid proteases (aspartyl peptidases). It forms a 1:1 complex with proteases such as pepsin, renin, cathepsin D, bovine chymosin, and protease B (Aspergillus niger). The inhibitor is highly selective and does not inhibit thiol proteases, neutral proteases, or serine proteases. Solubilized γ-secretase and retroviral protease are also inhibited by Pepstatin A. It has been used to characterize proteases from several sources.
Pepstatin potently inhibits the HIV protease and other aspartic proteases, such as pepsin, renin, cathepsin D, chymosin, protease B from Aspergillus niger, and acid proteases of microbial origin.
Potent inhibitor of acid proteases, including pepsin, renin and cathepsin D and many microbial aspartic proteases. Effective concentration 1 μM. Stable for about 1 day.
Preparation Note
Working concentration: 0.7 μg/ml (1 μM)
Working solution: Recommended solvent is methanol (1 mg/ml), ethanol, DMSO or glacial acetic acid.
Pepstatin is insoluble in pure water, but it is possible to produce an aqueous solutions with methanol (1.5–2.0 mg/ml), ethanol (1 mg/ml if allowed to sit overnight) or DMSO. Pepstatin is also soluble in acetic acid (6 N, 300 μg/ml) and pyridine. Solubility in NaCl solution is not known. Sodium or magnesium salts of pepstatin are water-soluble.
Stock solution: 1.4 mg pepstatin/mI (2 mM), in methanol
Storage conditions (working solution): -15 to -25 °C
Pepstatin can be dissolved at 1 mg/ml in 10% (v/v) acetic acid in methanol (9:1 methanol:acetic acid). The inclusion of acetic acid may be necessary to dissolve this peptide in methanol or DMSO. It has been dissolved at 1 to 2 mg/ml in ethanol, but heat may be required for complete dissolution. Solutions of Pepstatin A can be heated as high as 60 °C without any decomposition of the peptide.
Stock solutions at 1 mg/ml are stable at least a week at 4 °C. A 1 mM solution in methanol or DMSO is stable for months at -20 °C. If solutions become darker yellow, the reagent is hydrolyzing.
A working concentration of 1 μM is stable for at least one day at room temperature.
Soluble in methanol to approximately 1 mg/ml. Also soluble to 1 mg/ml in ethanol if allowed to sit overnight, and to 300 μg/ml in 6 N acetic acid. Stable for at least one week at 2 to 8 °C, or one month when stored in aliquots at -15 to -25 °C.

Analysis Note
Purity tested by HPLC.
Other Notes
For life science research only. Not for use in diagnostic procedures.