Fig. 1: Comparison of MDH activities.
From: Enhanced succinic acid production by Mannheimia employing optimal malate dehydrogenase
a SA biosynthetic pathway in the M. succiniciproducens PALK strain. Deleted genes are indicated as green thunder symbol. Key enzymes in SA production are indicated as red arrows. GLC glucose, PEP phosphoenolpyruvate, GOL glycerol, PYR pyruvate, LAC lactate, ACO acetyl-CoA, ACP acetyl-phosphate, ACT acetate, OAA oxaloacetate, MAL malate, FUM fumarate, SUC succinate, SCO succinyl-CoA, AKG alpha-ketoglutarate, CIT citrate, PCKA phosphoenolpyruvate carboxylase, LDHA lactate dehydrogenase, PTA phosphate acetyltransferase, ACKA acetate kinase, MDH malate dehydrogenase, FUMC fumarate hydratase, FRD fumarate reductase, MQred menaquinol. b The relative activities of four MDHs from various SA producers, including M. succiniciproducens, C. glutamicum, E. coli, and Y. lipolytica, in comparison with the activity of MsMDH (n = 3 independent experiments). Data are presented as mean values ± standard deviation. c Optimal pH of MsMDH and CgMDH (n = 3 independent experiments). Data are presented as mean values ± standard deviation. The specific activities at pH 10.0 were determined from a single data. d Catalytic performances of MsMDH and CgMDH at different pH (n = 3 independent experiments). Data are presented as mean values ± standard deviation. e kcat, f km, g kcat/km, and h ki values of MsMDH and CgMDH at different pH. Red and blue lines represent MsMDH and CgMDH, respectively. The ki value of CgMDH at pH 9.0 is shown in number because its value is significantly higher than the rest of the ki values. Data e–h are presented as parameters ± standard error. The standard errors from determining the kinetic parameters using OriginPro 2019 software (n = the number of mean velocity data at specific pH) are shown as bars.
