BINDING OF GLYCOLATE OXIDASE TO PEROXISOMAL MEMBRANE AS AFFECTED BY LIGHT

The stability of the bond of glycolate oxidase to the peroxisomal membrane obtained from etiolated barley leaves, (Hordeum vulgare L. var Dvir) is affected by the pH of the homogenization medium. Peroxisomes isolated at pH 4 or 10 retain glycolic oxidase, while peroxisomes isolated at pH 69 loose this enzyme during centrifugation. Preillumination of whole seedlings, detached leaves or even homogenates changes the effect of pH on the retention of glycolate oxidase‐attachment which is strengthened at pH 9–10 and becomes very loose at pH 4–7. White and red light are responsible for the effect described. Far red light reverses this effect of red light. Illumination induces a change in the isoelectric point (IpH) of peroxisomes without affecting the IpH of soluble enzymes. This red light‐induced change on IpH of microbodies is not reversed by far red light. The possible effects of light on peroxisomal membrane properties and on modulation of glycolate oxidase binding are discussed.