TABLE 2

Kinetic parameters of NagB measured with respect to the GlcN-6P concentrationa

NagB conditionsMean ± SD
NagB activityVmax (U/mg)Hill coefficientKhalf (mM)
pH 8.1, 0.4 mM GlcNAc-6P+U-PII90 ± 111.3 ± 0.33.6 ± 0.8
–PII11.3 ± 1.81.6 ± 0.82.9 ± 0.7
+PII16.8 ± 2.01.0 ± 0.42.3 ± 0.6
pH 7.8, no GlcNAc-6P+NanE5.4 ± 0.42.1 ± 0.34.8 ± 0.5
–NanE3.5 ± 0.92.1 ± 0.88.0 ± 2.0
pH 6.8, 0.2 mM GlcNAc-6P+NanE28.9 ± 3.51.9 ± 0.62.0 ± 0.4
–NanE13 ± 1.31.4 ± 0.41.9 ± 0.4
  • a The kinetic parameters of NagB were measured with respect to the GlcN-6P concentration in the presence or absence of PII or U-PII with 0.4 mM GlcNAc-6P at pH 8.1 and in the presence or absence of NanE at pH 7.8 (no GlcNAc-6P) or at pH 6.8 with 0.2 mM GlcNAc-6P. “U” indicates micromoles per minute. The pH values used were those that appeared to give the largest activation of NagB.