Table 3. Effect of Mutations on the Activation Barrier (ΔG⧧)OMP for Decarboxylation of OMP Catalyzed by Wild-Type OMPDC, and by Previously Mutated OMPDCa.
(ΔΔGX∓)OMP (kcal/mol)b |
||||
---|---|---|---|---|
mutated OMPDC | Q215A | Y217F | R235A | ∑(ΔΔGX∓)OMPc |
wild type | 2.2 | 2.4 | 5.6 | 10.2 |
single mutantd | 2.5 (R235A) | 2.5 (Q215A) | 5.8 (Q215A) | 10.8 |
2.3 (Y217F) | 3.2 (R235A) | 6.3 (Y217F) | 11.8 | |
double mutant | 2.8 | 3.5 | 6.8 | 13.4 |
For OMPDC-catalyzed decarboxylation at 25 °C, pH 7.1 (30 mM MOPS), and ionic strength of 0.105 (NaCl).
The effect of the point mutation on (ΔG⧧)OMP for decarboxylation of OMP catalyzed by the precursor enzyme, calculated from the ratio of values of kcat/Km for the precursor and mutant enzymes.
The sum of the effects of the Q215A, Y217F, and R235A mutations on (ΔΔGX∓)OMP.
The enzyme that was mutated is given in parentheses.