Division of Biological and Medical Research, Argonne National Laboratory, Argonne, Illinois 60439.
Plant Physiol. 1967 Mar;42(3):421-4. doi: 10.1104/pp.42.3.421.
Lipoxidase, in the cotyledons of squash (Cucurbita moscata) seedlings grown in the dark, reached its peak activity on the fifth day and then declined to its lowest activity on the eighth day. Under continuous irradiation, the rate of enzyme disappearance was accelerated by red (655 mmu) and was retarded by far-red (735 mmu) radiation. Acceleration of enzyme disappearance caused by red light was reversed repeatedly by far-red light in seedlings that received an initial exposure to red radiation. These responses were independent of the duration of irradiation at each of the alternating wavebands. No change was observed when the white light was administered either 24 hours before or 24 hours after the red, far-red treatment.The lipoxidase system of the seedlings given an initial exposure to far-red radiation also responded reversibly to alternating far-red, red extended exposures, but it failed to respond reversibly when short exposures were employed. Similarly, no change occurred in these seedlings when either pre- or post-treatment with the white light was applied.These results demonstrate that the capacity of lipoxidase to act reversibly depends primarily on the duration of exposure and on the kind of light (red or far-red) to which the seedlings were exposed initially. In spite of these variations, lipoxidase metabolism can be considered an additional biochemical manifestation of red, far-red reaction that operates in the photomorphogenesis of plants.
在黑暗中生长的南瓜（Cucurbita moscata）幼苗子叶中的脂肪氧化酶，在第五天达到最高活性，然后在第八天降至最低活性。在连续照射下，酶失活的速度被红光（655nm）加速，被远红光（735nm）辐射延迟。在最初暴露于红光下的幼苗中，红光引起的酶失活加速被远红光反复逆转。这些反应独立于每个交替波段的照射时间。当白光在红光、远红光处理前 24 小时或后 24 小时给予时，没有观察到变化。在接受最初远红光处理的幼苗中，脂肪氧化酶系统也对交替的远红光、红光扩展暴露有可逆反应，但当采用短时间暴露时，它无法产生可逆反应。同样，当白光在处理前或处理后应用时，这些幼苗中也没有发生变化。这些结果表明，脂肪氧化酶的可逆作用能力主要取决于暴露时间和幼苗最初暴露的光（红光或远红光）的种类。尽管存在这些变化，但脂肪氧化酶代谢可以被认为是植物光形态建成中运行的红光、远红光反应的另一种生化表现。
