Department of Biological Sciences, Union College, Schenectady, New York 12308.
Plant Physiol. 1985 Oct;79(2):515-9. doi: 10.1104/pp.79.2.515.
In extracts from the youngest leaves of Avena sativa, Hordeum vulgare, Zea Mays, Pisum sativum, Phaseolus vulgaris, Lactuca sativa, and four pyrrolizidine alkaloid-bearing species of Heliotropium, the activities of ornithine decarboxylase, close to V(max), ranged between traces and 1.5 nanomoles per hour per gram fresh weight when based on putrescine formed during incubation with labeled ornithine. The arginine decarboxylase activities in the same extracts ranged between 8 and 8000 nanomoles per hour per gram fresh weight being lowest in the borages and highest in oat and barley. alpha-Difluoromethylornithine and alpha-difluoromethylarginine inhibited ornithine and arginine decarboxylases, respectively, in all species. Agmatine, putrescine, spermidine, and spermine were found in all, diaminopropane in eight, and cadaverine in three species.No correlation was observed between arginine or ornithine decarboxylase level and the levels of total polyamines. The in vitro decarboxylase activities found in the borages cannot explain the high accumulation of putrescine-derived pyrrolizidines in their youngest leaves if the pyrrolizidines are produced in situ from arginine and/or ornithine as precursors; other possibilities are discussed.In assays of ornithine decarboxylase, an interference of decarboxylation not due to this enzyme was observed in extracts from all species. In arginine decarboxylase assays, the interfering decarboxylation as well as the interference of arginase were apparent in two species. Addition of aminoguanidine was needed to suppress oxidative degradation of putrescine and agmatine during incubation of extracts from pea, bean, lettuce, Heliotropium angiospermum, and Heliotropium indicum.
在从小麦、黑麦、玉米、豌豆、菜豆、莴苣和 4 种含吡咯里西啶生物碱千里光属植物的幼嫩叶片提取物中，以标记鸟氨酸孵育时形成的腐胺为基础，鸟氨酸脱羧酶的活性（接近于 Vmax），在痕量到每克鲜重每小时 1.5 纳摩尔之间。同一提取物中的精氨酸脱羧酶活性范围为每克鲜重每小时 8 到 8000 纳摩尔，在藜科植物中活性最低，在燕麦和大麦中活性最高。α-二氟甲基鸟氨酸和α-二氟甲基精氨酸分别抑制所有物种中的鸟氨酸和精氨酸脱羧酶。胍丁胺、腐胺、亚精胺和精胺在所有物种中均有发现，二氨基丙胺在 8 种物种中有发现，尸胺在 3 种物种中有发现。没有观察到精氨酸或鸟氨酸脱羧酶水平与总多胺水平之间存在相关性。如果吡咯里西啶是由精氨酸和/或鸟氨酸作为前体原位产生的，那么在藜科植物幼嫩叶片中发现的体外脱羧酶活性不能解释腐胺衍生的吡咯里西啶的高积累；其他可能性也在讨论中。在鸟氨酸脱羧酶测定中，观察到所有物种的提取物中存在非由该酶引起的脱羧干扰。在精氨酸脱羧酶测定中，在 2 种物种中，干扰性脱羧作用以及精氨酸酶的干扰都很明显。在豌豆、菜豆、莴苣、天蓝葵和印度千里光的提取物孵育过程中，需要添加氨基胍来抑制腐胺和胍丁胺的氧化降解。
