Myo-inositol oxygenase from oat seedlings

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Abstract
Enzyme preparations from oat seedlings showing the activity ofmyo-inositol oxygenase (E.C.1.13.99.1) have been described previously. In contrast tomyo-inositol oxygenase preparations from other sources, e.g. rat kidney or yeast, the oat enzyme seemed to exhibit a somewhat less stringent activity, acting on other inositols and inositol methyl ethers as well as onmyo-inositol. By purification of the enzyme present in the extract from oat seedlings with the help of an affinity gel specific for enzymes acting onmyo-inositol a homogeneous enzyme preparation was obtained, which shows the same strict specificity as themyo-inositol oxygenase from other sources. It has a molecular weight of 62,000 and tends to aggregate to oligomers (up to tetramers) under physiological pH-values; in more alkaline media dissociation to monomers is observed. The action on the other inositols and inositol methyl ethers is apparently due to one or more other enzymes, which are also adsorbed on the affinity gel, but can be separated from themyo-inositol oxygenase by elution with increasing concentrations ofmyo-inositol.