Tris electrophoresis purity reagent

Bovine serum albumin (BSA) and sodium hydroxide were obtained from Sigma–Aldrich (MO, USA). Glutaraldehyde (crosslinker) solution (25%) and Ethanol 96% were provided by VWR BDH Prolabo (VWR, Paris, France). DPBS (+) and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich. Disodium phosphate and monosodium phosphate were provided by Merck GmbH. Electrophoresis gel components, which consisted of acrylamide 40%, Tris electrophoresis purity reagent, sodium dodecyl sulfate, ammonium persulfate, and tetramethylethylenediamine (TEMED), were all provided by Biorad. Ultra-pure water was purified using a synergy unit system (Millipore, Villeurbanne, France).

The biological reagents used in this study were BSA (lyophilized powder, 66 kD) (Equitech-Bio, Kerrville, TX, USA) and pharmaceutical grade capsaicin (≥ 99%) from Capsicum spp. (Handim Chemical Co., Ltd, Shanghai, China). The chemical reagents were glutaraldehyde (25%) (Electron Microscopy Science, Hatfield, PA, USA), sodium chloride analytical grade (Merck, Darmstandt, Germany), acetonitrile (≥ 99.9%) (Sigma-Aldrich, St Louis, MS, USA) and absolute ethanol (≥ 99.8%) (Merck, Darmstandt, Germany). Polyacrylamide gel electrophoresis components, which consisted of acrylamide (40%), tris electrophoresis purity reagent, sodium dodecyl sulfate, ammonium persulfate, and tetramethylethylenediamine (TEMED) (Bio-Rad Laboratories, Richmond, CA, USA), Coomassie brilliant blue G-250 (Sigma-Aldrich, St Louis, MS, USA) and acetic acid glacial HPLC grade (Merck, Darmstandt, Germany) for Coomassie staining solution (CBB). For derivatization of free amino acids methanol HPLC grade (Sigma-Aldrich, St Louis, MS, USA), triethylamine (Sigma-Aldrich, St Louis, MS, USA), and phenyl isothiocyanate (Sigma-Aldrich, St Louis, MS, USA) were used.