*4.6. Blue-Native PAGE (BN-PAGE)*

BN-PAGE was performed in linear 4% to 16% (*w*/*v*) polyacrylamide-gradient gels [28,49,50]. Before running the BN-PAGE, sample aliquots (10 μL) containing 20 μg of C-LrtA were mixed with 1 μL of 5% Coomassie Brilliant blue G stock solution in 750 mM aminocaproic acid. Electrophoresis was initiated at 85 V for 30 min, and then continued at 200 V for 2.5 h, at 4 ◦C. After electrophoresis, the gels were stained overnight with colloidal Coomassie Blue G 250 [51]. In these gels, it is the negative charge from the Coomassie Blue, capable of binding to the hydrophobic protein surfaces, what determines the electrophoretic mobility. The technique is a method of choice to study the organization of protein complexes in their native state [28,49–51].
