2.3. Solubility measurement of MRPs
Ten millilitres of an MRP sample was diluted with 10 ml of various
buffers (0.05 M sodium phosphate buffer, pH 5, 6.5 and 8;
0.05 M sodium hydrogen carbonate buffer, pH 9.5 and 11; 0.05 M
citrate buffer, pH 3.5 and 0.05 M KCl–acetic acid buffer, pH 2).
The pH of the solution was readjusted to the buffer pH with
0.1 M HCl or NaOH. Samples were centrifuged for 20 min at
10,000g. Protein content in the supernatant was determined by
the Kjeldahl method. Solubility was expressed as a percentage of
protein in the supernatant to the total protein content.