TABLE 2

Kinetic characteristics of glucokinase ins454A, W99L, and M197I

MutantsYield (mg/l)kcat(sec−1)Glucose S0.5(mmol/l)ATP Km(mmol/l)nH(Hill number)Activity indexActivation by GKA (fold)EC50for GKA (μmol/l)
ins454A10.9 ± 3.153.2 ± 2.91.1 ± 0.10.31.239.5 ± 1.7No activationN/A
W99L19.9 ± 1.785.6 ± 3.12.9 ± 0.10.41.613.3 ± 0.811.84.3
M197I62.1 ± 0.338.1 ± 4.52.6 ± 0.21.51.64.8 ± 0.311.94.9
M197L34.554.55.41.01.43.813.96.2
M197V25.144.72.60.51.78.013.13.5
M197A36.453.33.20.31.77.014.73.8
M197T26.753.94.10.51.64.418.35.5
M197F40.321.254.60.21.30.18.66.1
M197K36.43.7886.70.21.10.0313.69.3
M197D27.710.3197.00.31.10.036.02.8
M197E6.8221.056.21.30.20.19.02.7
Wild type43.4 ± 3.862.3 ± 4.87.6 ± 0.20.41.71.5 ± 0.115.8 ± 0.66.9 ± 0.4
  • Kinetic data of purified expressed GST-tagged glucokinase with hyperinsulinism-causing ins454A (child 1), W99L (child 2), and M197I (child 3) mutations. EC50relates to the activity index. GKA, glucokinase activator; EC50, half-maximal effective concentration.