FIGURE 7.

Acid-induced substrate promiscuity in α-keto acid dehydrogenases. A, generalized reaction scheme for α-keto acid dehydrogenases, with the table showing specific examples and the corresponding R group for each substrate/product pair. B, the ability of LDH to catalyze the native back reaction of MDH (i.e. OAA to malate) was measured at various pH values, assayed spectrophotometrically as NADH consumption. C, generation of malate in this system was also assayed by LC-MS/MS. The data are means ± S.E., n = 4. *, p < 0.05 (two-way ANOVA followed by Student's t test) compared with corresponding value at pH 7.4.