under optimum conditions ( ph 7.5 , mg2+ present ) , the carbon isotope effect is k12/k13 = 0.9989 +/- 0.0004 for the carboxyl carbon undergoing decarboxylation and hydrogen isotope effects are vmaxh/vmaxd = 1.09 +/- 0.04 and ( vmax/km ) h/ ( vmax/km ) d = 0.76 +/- 0.12 with threo-d , l- [ 2-2h ] isocitric acid .
C0007017
carbon isotope
C0022262
isotope