Table III.

Maize root HXK kinetic parameters for the phosphorylation of hexoses

Glc3-aMan3-OMG3-aATP
K m (μmol L−1)76 ± 9105 ± 4021,000 ± 7,00042 ± 8
V max (μmol min−1 mg protein−1)2.52 ± 0.311.26 ± 0.060.007 ± 0.0022.16 ± 0.32
103 ×V max/K m(min−1 mg protein−1L)33123.10−4 51

The K m and V max values were calculated using the Lineweaver-Burk reciprocal plot method. Data are the mean of three measurements from two independent HXK preparations.

    • F3-a HXK activity was inhibited to the same extent with either Glc (2 mm) or 3-OMG (50 mm), when measured in the presence of either 10 mm ZnCl2(55% inhibition) or 0.5 mm ADP (15% inhibition). With 10 mm mannoheptulose, Glc and 3-OMG phosphorylations were inhibited by 31% and 78%, respectively.