Figure 3.

 Quantification of the different forms of spiked catalase using recombinant hemagglutinins from A/Vietnam/1203/2004 as internal standard. A known quantity of catalase in the form of intact, predigested, or mixture of synthetic peptides was spiked into a preparation of A/Wisconsin/15/2009 at the concentration of 60·1 μg/ml. Correction factors determined from the ratio of the measured and expected concentrations of intact, predigest, and synthetic peptide forms of catalase were 0·88, 0·95, and 1·73, respectively. Data shown are representative of the results of three biological replicates, each of which was obtained from three technical replicates.