Digitonin (5%)

Digitonin, also known as digitin, is a mild, non-ionic detergent with a cholesterol-like structure that allows it to water-solubilize lipids. It is useful for permeabilizing cells and can be used as a cytotoxicity chemistry positive control. In addition, it preserves the native lipid environment in membrane protein complexes and can be used to solubilize membrane-bound proteins. Digitonin has a molecular formula of C₅₆H₉₂O₂₉ and molecular weight of 1229 Daltons.

Digitonin detergent solution has many more applications. It is used to prepare native protein samples for analysis on the NativePAGE Gel System. Included in the NativePAGE Sample Prep Kit (Cat No. BN2008), this ready-to-use detergent solution improves solubility of hydrophobic and membrane proteins during sample preparation. Samples prepared with 10% DDM, 5% digitonin, or the NativePAGE Sample Prep Kit are compatible with NativePAGE Novex Bis-Tris Gels for native electrophoresis and have increased resolution and reduced streaking. In addition, before structural determination by cryo-EM or crystallization, digitonin can be used to solubilize membrane proteins (typically at 1–2% w/v) and as a wash buffer.

It is important to note for sample preparation that the digitonin detergent micelle size is ∼70 kDa and is typically used at a concentration that is 1–2X the critical micelle concentration (CMC).

Furthermore, digitonin can be used as a spike in purified protein at CMC concentration to help with particle distribution and preferred orientation on grid during the vitrification process. In addition, digitonin provides efficient antibody penetration into tissue sections and is compatible with immunohistochemistry (IHC) staining. Digitonin at a final concentration of 0.2–0.5% in buffer is compatible with IHC.

NOTE: If the 5% digitonin solution precipitates out of solution, warm the solution at 37°C and gently shake to dissolve the precipitate.