COMPARISON OF THE ABILITIES OF TRICHLOROACETIC, PICRIC, SULFOSALICYLIC, AND TUNGSTIC ACIDS TO PRECIPITATE PROTEIN HYDROLYSATES AND PROTEINS

Abstract

ABSTRACT The abilities of picric, sulfosalicylic (SSA), tricbloroacetic (TCA), and tungstic acids to precipitate a partial hydrolysate of egg albumin and several proteins were examined. After precipitation of the hydrolysate with SSA, TCA, and tungstic acid respectively, it was found that 88%, 79%, and 69% of the nitrogen remained in solution. The average size of the peptides in the supernatants varied from 330 to 380 daltons. The ability to precipitate native proteins varied with the precipitant and the protein. Tungstic acid precipitated both bovine serum albumin and β‐lactoglobulin completely at low concentration (0.5% final concentration, w/v). Bovine serum albumin was precipitated by 3% TCA or SSA but, β‐lactoglobulin was not completely precipitated until the concentrations had been increased to 10% and 20%, respectively. Pretreating β‐lactoglobulin with sodium dodecylsulfate increased the amount precipitated by SSA and TCA.