van Lookeren Campagne M M, Löwik C G
Biochim Biophys Acta. 1985 Jul 30;846(1):55-63. doi: 10.1016/0167-4889(85)90110-7.
By the use of an in vivo assay, ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) is shown to be developmentally regulated in Dictyostelium discoideum. High levels of cAMP can induce ornithine decarboxylase activity in preaggregative cells kept in shaking suspension, under similar conditions as where other markers for development can also be induced. This induction by cAMP is solely dependent on the total amount of cAMP to which the cells have been exposed, and not on the manner of cAMP addition. Induction of ornithine decarboxylase activity, when measured in vitro, is caused by both an increase in total enzyme activity and by a proportional increase in activity of the high-affinity form for the cofactor pyridoxal phosphate. When measured in vivo, an additional regulatory mechanism seems to be involved. Kinetic studies with the competitive inhibitor putrescine suggest that in cAMP-stimulated cells the low affinity form of the enzyme may also be active in vivo.
通过体内测定法表明，在盘基网柄菌中，鸟氨酸脱羧酶（L-鸟氨酸羧基裂解酶，EC 4.1.1.17）受发育调控。在与诱导其他发育标记物相似的条件下，高浓度的环磷酸腺苷（cAMP）可诱导处于振荡悬浮状态的聚集前期细胞中的鸟氨酸脱羧酶活性。cAMP的这种诱导作用仅取决于细胞所接触的cAMP总量，而不取决于cAMP的添加方式。体外测定时，鸟氨酸脱羧酶活性的诱导是由总酶活性的增加以及对辅因子磷酸吡哆醛的高亲和力形式的活性成比例增加所致。体内测定时，似乎还涉及一种额外的调节机制。用竞争性抑制剂腐胺进行的动力学研究表明，在cAMP刺激的细胞中，该酶的低亲和力形式在体内可能也具有活性。
