sentence: Dephosphorylation reactions contained 150 nM SixA , SixA ( H8A ) , or neither and were incubated at 30 ° C. Samples at each time point were quenched by mixing with 3 × SDS-PAGE loading dye ( 6 % SDS , 30 % glycerol , 195 mM Tris HCl , 15 % β - mercaptoethanol , 0.015 % bromophenol blue , pH 8.8 ) .