title: Spicy SDS-PAGE gels: curcumin/turmeric as an environment-friendly protein stain.
abstract: Gel proteins are commonly stained with calorimetric/fluorescent dyes. Here, we demonstrate that heat-solubilized curcumin can serve as a nontoxic and environment-friendly fluorescent/colorimetric reversible protein stain. Curcumin, the yellow pigment found in the rhizomes of the perennial herb Curcuma longa (turmeric), is insoluble in aqueous solvents. However, heat (100°C) solubilization in water renders 1.5% of curcumin soluble. Curcumin solubilized by ethanol or alkali is ineffective in staining proteins. Heat solubilized curry spice turmeric stains proteins similarly. Staining is achieved in 30 min, with a sensitivity almost equaling that of Coomassie Brilliant Blue (CBB). Destaining is not required, and excess curcumin/turmeric can be discarded into the sink. Binding of proteins by silver inhibits curcumin binding, suggesting similarity of protein binding by silver and curcumin. It costs $1.5-2.0 to stain a mini-gel with curcumin, while turmeric costs less than 0.005 cent. CBB staining/destaining costs about 2 cents. However, CBB is toxic and its use necessitates specialized disposal efforts. Curcumin/turmeric, thus, can serve as an ideal nontoxic protein stain.
authors.affiliation: Department of Veterans Affairs, University of Oklahoma Health Sciences Center, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA. biji-kurien@omrf.org
authors.forename: Biji T
authors.initials: BT
authors.lastname: Kurien
authors.forename: Yaser
authors.initials: Y
authors.lastname: Dorri
authors.forename: R Hal
authors.initials: RH
authors.lastname: Scofield
mesh_terms: D002021:Buffers; D002457:Cell Extracts / Q000737:chemistry / Q000302:isolation & purification; D004396:Coloring Agents / Q000737:chemistry*; D030024:Curcuma / Q000737:chemistry*; D003474:Curcumin / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D000431:Ethanol / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D055772:Green Chemistry Technology / Q000379:methods*; D006367:HeLa Cells; D006801:Humans; D057230:Limit of Detection; D012394:Rosaniline Dyes / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000302:isolation & purification; D012835:Silver Nitrate / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013194:Staining and Labeling / Q000379:methods*; D014867:Water / Q000737:chemistry
chemical_list: D002021:Buffers; D002457:Cell Extracts; D004396:Coloring Agents; D005456:Fluorescent Dyes; D012394:Rosaniline Dyes; D012997:Solvents; D014867:Water; D012710:Serum Albumin, Bovine; D000431:Ethanol; D012972:Sodium Hydroxide; D012835:Silver Nitrate; D003474:Curcumin; C004692:coomassie Brilliant Blue; D004121:Dimethyl Sulfoxide