Determination of Optimum pH of p30 and p72 Protein
An indirect ELISA was used to test the supernatant of the gold-labeled solution at pH 4–9 after centrifugation. When the OD450nm value of the supernatant was at its lowest, the unlabeled protein content in the supernatant was also at its lowest, implying that the protein bound to the surface of gold particles was at its highest at this pH. As shown in Figures 5A and 5B , the OD450nm of the supernatant was lowest when the pH of the colloidal gold solution was 8 and 7. Therefore, the optimal pH values for the p30 and p72 proteins were 8 and 7, respectively.
Figure 5│ Determination of the optimal pH value for p30 protein (A) and p72 protein (B). Error bars correspond to the standard deviation of the data (n = 3).