Determination of substrate specificity of MsmR and MsmE by thermal shift assay. (A) Alteration of the melting temperature of purified MsmR–Strep-tag (concentration) in the absence of effectors was compared to the presence of galactose, melibiose, or raffinose with the final concentration of 10 mM. (B) Purified His6-MsmE was mixed with different effectors (10 mM), i.e., galactose, melibiose, raffinose, and stachyose, and its melting temperature was measured.