Table II.

Activities of HXK, neutral phosphatase, and G6P phosphatase in clear homogenates of maize root tips and in partially purified HXK fraction

ConditionHXKNeutral PhosphataseG6P Phosphatase
nmol min−1 tip−1
Control4.8 ± 0.84.45 ± 0.150.9 ± 0.5
Starvation2.9 ± 0.79.1 ± 0.11.9 ± 0.6
3-OMG (100 mm) 2.7 ± 0.710.1 ± 0.81.8 ± 0.5
μmol min−1 mg protein−1
Purified HXK2.5 ± 0.30.024 ± 0.001n.d.

Excised root tips were incubated either during 4 h with 200 mm Glc (control) or during 48 h in a medium either devoid of carbon substrate (starvation) or containing 100 mm 3-OMG. Data are the mean of three independent experiments for clarified homogenates and for purified HXK. n.d., Not determined.