A specific sucrose phosphatase from plant tissues

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Abstract
A phosphatase that hydrolyses sucrose phosphate (phosphorylated at the 6-position of fructose) was isolated from sugar-cane stem and carrot roots. With partially purified preparations fructose 6-phosphate, glucose 6-phosphate, fructose 1-phosphate, glucose 1-phosphate and fructose, 1,6-diphosphosphate are hydrolysed at between 0 and 2% of the rate for sucrose phosphate. The activity of the enzyme is increased fourfold by the addition of Mg2++ ions and inhibited by EDTA, fluoride, inorganic phosphate, pyrophosphate, Ca2++ and Mn2+ ions. Sucrose (50 m[image]) reduces activity by 60%. The enzyme exhibits maximum activity between pH 6.4 and 6.7. The Michaelis constant for sucrose phosphate is between 0.13 and 0.17 m[image]. At least some of the specific phosphatase is associated with particles having the sedimentation properties of mitochondria. A similar phosphatase appears to be present in several other plant species.