Fig. 2

Comparison of different periplasmic extraction methods. a Western blotting and densitometry analysis showing the presence and recovery of ExoA-CPS4 glycoproteins obtained with both the lysozyme and heat-based methods of periplasmic extraction. Lanes 5 and 9: Proteinase K digests. Relative quantification based on pixel intensity; b Semi-quantitative sandwich ELISA analysis of ExoA-CPS4 glycoproteins in periplasmic extracts. ExoA-coupled CPS4 glycan and ExoA protein (His) were quantified independently. Statistical significance (*) using an unequal variance two-tailed t-test is considered in all experiments when p ≤ 0.05; c Western blotting showing the presence of ExoA-CPS4 glycoproteins in periplasmic extracts obtained with some of the conditions listed in Table 3 and densitometry results of protein (red) and glycan (green) quantities based on pixel intensity normalised to the control condition