The UDP-D-glucose 4-epimerase activity of the spruce callus culture.
1991
Bilisics L. | Kakoniova D. | Kubackova M. | Liskova D.
Spruce callus culture was used as a source for the extraction and partial purification of cytoplasmic UDP-D-glucose 4-epimerase. The enzyme has properties similar to UDP-D-glucose 4-epimerase of various plant, sources the endogenous activator of which is tightly bound NAD+. The apparent Michaelis constant value of this enzyme for UDP-D-glucose was 3.55 mmol.l-1. The temperature and pH optima of UDP-D-glucose 4-epimerase were 45 degrees centigrade and pH 9.0. Reaction rate is linear with the time and enzyme protein content the first 10 minutes. In the presence of glycerol the enzyme remained stable for 30 days at pH 9.0 and minus 30 degrees centigrade. Exogenous NAD+ was not required for enzymic activity, but removal of endogenous NAD+ caused inactivation. The UDP-D-glucose 4-epimerase activity can be affected by auxins and L-glutathione, respectively.
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