Peltzer D, Schwanz P, Polle A
Forstbotanisches Institut der Georg-August Universität Göttingen, Germany.
Free Radic Res. 1999 Dec;31 Suppl:S181-5. doi: 10.1080/10715769900301481.
Green and white variegated leaves of Coleus blumei, Benth. were separated into albino and green sections and used to determine the distribution of vitamin C and L-galactose dehydrogenase activity, an enzyme supposed to be involved in ascorbate metabolism, in heterotrophic and autotrophic foliar fractions. Both green and white sections contained vitamin C and activity of L-galactose dehydrogenase. However, in the white parts mainly dehydroascorbate was found, whereas in the green parts the redox state of the ascorbate system varied with light or dark conditions. Characterisation of L-galactose dehydrogenase from illuminated green leaf sections showed increasing activity with increasingly alkaline pH-values and a temperature optimum of 25 degrees C. Since these properties were slightly different than those of L-galactose dehydrogenase activities obtained from albino or darkened green leaf sections, we suggest that the enzyme may be light-modulated.
唇形科鞘蕊花属植物彩叶草的绿白相间的杂色叶片被分成白化和绿色部分，用于测定维生素C和L-半乳糖脱氢酶活性的分布，L-半乳糖脱氢酶是一种被认为参与抗坏血酸代谢的酶，存在于异养和自养叶部分中。绿色和白色部分均含有维生素C和L-半乳糖脱氢酶活性。然而，在白色部分主要发现脱氢抗坏血酸，而在绿色部分，抗坏血酸系统的氧化还原状态随光照或黑暗条件而变化。对光照下绿色叶片部分的L-半乳糖脱氢酶的表征显示，随着pH值逐渐升高，活性增加，最适温度为25℃。由于这些特性与从白化或暗化的绿色叶片部分获得的L-半乳糖脱氢酶活性略有不同，我们认为该酶可能受光调节。
