2.3. GlxI Activity Assay

The procedure was performed by following our previous procedures [9]. Monitoring the absorbance of 240 nm by spectrophotometry was applied to measure S-d-lactoylglutathione formation in a GlxI reaction solution containing 8 mM MG, 1 mM glutathione (GSH, Sigma-Aldrich, St. Louis, Missouri, United States), 15 mM MgSO₄, and 0.2 M imidazole-HCl, pH 7.0 at 25 °C. For 200 μL of reaction, 20 μL of 0.1 μg/μL cell lysate were added to 180 μL of GlxI reaction buffer. GlxI activity was obtained by calculating the slope of absorbance over time of the catalytic velocity curve.