Hexokinases of tobacco leaves: changes in the cytosolic and non-cytosolic isozyme complexes induced by tobacco mosaic virus infection

Šindelář, Luděk; Šindelářová, Milada
BIOLOGIA PLANTARUM 47 [3]: 413-419, 2003

Klíčová slova: Nicotiana tabacum; hexokinase; TMV
Abstrakt: Changes in the cytosolic (soluble) and the non-cytosolic (particulate) isozyme composition of hexokinases were studied by ion exchange chromatography after subcellular fractionation in TMV infected tobacco leaves. Three main isozyme complexes were obtained: one particulate fraction (particulate hexokinase) and two soluble fractions (soluble hexokinase and soluble fructokinase). The total fructokinase activities were nearly twice higher than the total glucose activities. The total particulate glucokinase and fructokinase activity were increased to 120% in TMV infected tissue. The sum of soluble glucokinase activity was increased to 175% and of fructokinase activity to 131% in TMV infected tissue. The isozymes isolated both from the healthy control and TMV-infected leaves had the similar elution profiles, displayed Michaelis-Menten kinetics, showed the identical profiles of pH optima and were Mg2+ dependent with the highest enzyme activity at equimolar Mg2+ and ATP concentration.
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