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Sodium dodecyl sulfate elicits the production of superoxide

Time:2015/11/24 5:56:00

Activation of NADPH-dependent superoxide production in a cell-free system by sodium dodecyl sulfate.

Sodium dodecyl sulfate (SDS) elicits the production of superoxide (O2-) by a cell-free system represented by sonically disrupted guinea pig peritoneal macrophages. O2- generation requires NADPH and a heat-sensitive cellular component, is proportional to the amount of macrophage protein, and exhibits a pH optimum of 6.5-7. The kinetic parameters of the SDS-stimulated enzyme are: Km (+/- S.E.) = 0.0367 +/- 0.003 mM NADPH and Vmax (+/- S.E.) = 73.46 +/- 9.09 nmol O2-/mg of protein/min. O2- production is dependent on the cooperation between a particulate subcellular component sedimentable at 48,000 X g and a cytosolic factor present in the 48,000 X g supernatant. The activity of both components is destroyed by heating at 80 degrees C. Pretreatment of intact macrophages with phorbol myristate acetate results in the partial removal of the requirement for cytosolic factor; SDS is now capable of activating the isolated 48,000 X g pellet. Among a large number of anionic, cationic, and nonionic detergents tested, only the anionic detergents SDS and sodium dodecyl sulfonate are capable of eliciting O2- production in the cell-free system, SDS being the more potent stimulant. It is proposed that the structural requirements that make these compounds capable of activating the O2- forming NADPH oxidase in a cell-free system are the presence of an anionic polar head and a long hydrophobic alkyl tail. We suggest that sodium salts of long chain unsaturated fatty acids that were found by us to be capable of stimulating O2- production in a cell-free system (Bromberg, Y., and Pick, E. (1984) Cell. Immunol. 88, 213-221) owe their activity to the fact that they function as anionic detergents.

Fluorescence detection of proteins in sodium dodecyl sulfate-polyacrylamide gels using environmentally benign, nonfixative, saline solution. Electrophoresis 20, 497-508

ABSTRACT SYPRO Tangerine stain is an environmentally benign alternative to conventional protein stains that does not require solvents such as methanol or acetic acid for effective protein visualization. Instead, proteins can be stained in a wide range of buffers, including phosphate-buffered saline or simply 150 mM NaCl using an easy, one-step procedure that does not require destaining. Stained proteins can be excited by ultraviolet light of about 300 nm or with visible light of about 490 nm. The fluorescence emission maximum of the dye is approximately 640 nm. Noncovalent binding of SYPRO Tangerine dye is mediated by sodium dodecyl sulfate (SDS) and to a lesser extent by hydrophobic amino acid residues in proteins. This is in stark contrast to acidic silver nitrate staining, which interacts predominantly with lysine residues or Coomassie Blue R, which in turn interacts primarily with arginine and lysine residues. The sensitivity of SYPRO Tangerine stain is similar to that of the SYPRO Red and SYPRO Orange stains - about 4-10 ng per protein band. This detection sensitivity is comparable to colloidal Coomassie blue staining and rapid silver staining pro