Department of Chemistry, University of Toledo, Toledo, Ohio 43606.
Plant Physiol. 1986 Dec;82(4):1139-44. doi: 10.1104/pp.82.4.1139.
A number of lipoxygenase isoenzymes were identified in developing soybean (Glycine max L. Merrill cv Provar) seeds and two have been partially characterized. In a study of lipoxygenase level in developing soybean seeds, the enzyme content increased markedly during development. Comparisons of the lipoxygenases from mature soybean seeds and immature seeds by isoelectric focusing, chromatofocusing, sodium dodecyl sulfate polyacrylamide gel electrophoresis and peptide mapping identified two categories of isoenzyme. The isoenzymes from immature seeds were found by electron paramagnetic resonance spectroscopy to be isolated at least in part as the high spin iron(III) or active form of the enzyme in contrast to lipoxygenases from mature seeds which were isolated as electron paramagnetic resonance silent, high spin iron(II) species. The discovery of increased levels of lipoxygenases during seed development and their isolation in an active form suggests that the enzyme may play a physiological role during the maturation process. The incorporation of iron-59 from the nutrient medium into lipoxygenase during culture of immature seeds was indicative of de novo synthesis of the enzyme. The efficiency of the iron uptake was high, as indicated by the level of radioactivity found in the enzyme (one gram atom of iron per mole of lipoxygenase).
在发育中的大豆（Glycine max L. Merrill cv Provar）种子中鉴定出了许多脂氧合酶同工酶，其中两种已部分得到表征。在发育中的大豆种子中脂氧合酶水平的研究中，该酶的含量在发育过程中明显增加。通过等电聚焦、色谱聚焦、十二烷基硫酸钠聚丙烯酰胺凝胶电泳和肽图谱比较成熟大豆种子和未成熟种子中的脂氧合酶，确定了两种同工酶类别。电子顺磁共振波谱研究表明，与成熟种子中的脂氧合酶不同，未成熟种子中的同工酶至少部分以高自旋铁（III）或酶的活性形式存在，而成熟种子中的脂氧合酶则以电子顺磁共振静默、高自旋铁（II）形式存在。在种子发育过程中脂氧合酶水平的增加及其以活性形式的分离表明，该酶在成熟过程中可能发挥生理作用。在未成熟种子的培养过程中，从营养培养基中掺入铁-59 到脂氧合酶中表明该酶是从头合成的。铁的摄取效率很高，如在酶中发现的放射性水平所示（每摩尔脂氧合酶一个铁原子）。
