Kandpal M, Tekwani B L
Division of Biochemistry, Central Drug Research Institute, Lucknow, India.
Life Sci. 1997;60(20):1793-801. doi: 10.1016/s0024-3205(97)00139-2.
The following observations are conjointly indicative of the presence of distinct energy-dependent, saturable and multiple polyamine transport systems in Leishmania donovani promastigotes, the causative agent for visceral leishmaniasis. Spermidine was influxed with as much as seven times higher rate than putrescine, while both spermidine and putrescine transporters exhibited equally high affinity for the respective polyamine. N-Ethylmaleimide arrested the complete functionality of both the transporters which could be restored by reduced glutathione. Putrescine transporter did not recognize spermine but spermidine was recognized to some extent, while spermidine transporter significantly recognized spermine but putrescine was absolutely spared. A few aromatic diamines viz., diaminobiphenyl and the analogs as well as aliphatic diamines viz., cadaverine and agmatine were selectively recognized by the putrescine transporter only. L. donovani promastigotes grown in presence of alpha-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, registered marked upregulation of putrescine transport while spermidine transport was only marginally induced. PA transport systems provide the alternative pool of polyamines in L. donovani promastigotes in the absence of an adequate intracellular PA repertoire.
以下观察结果共同表明，内脏利什曼病的病原体杜氏利什曼原虫前鞭毛体中存在独特的能量依赖型、可饱和且多种的多胺转运系统。亚精胺的流入速率比腐胺高出多达7倍，而亚精胺和腐胺转运体对各自的多胺均表现出同样高的亲和力。N-乙基马来酰亚胺使两种转运体的全部功能均被阻断，而还原型谷胱甘肽可使其恢复。腐胺转运体不识别精胺，但能在一定程度上识别亚精胺，而亚精胺转运体能显著识别精胺，但完全不识别腐胺。只有腐胺转运体能选择性识别一些芳香族二胺，即二氨基联苯及其类似物，以及脂肪族二胺，即尸胺和胍丁胺。在鸟氨酸脱羧酶不可逆抑制剂α-二氟甲基鸟氨酸存在的情况下生长的杜氏利什曼原虫前鞭毛体，腐胺转运显著上调，而亚精胺转运仅略有诱导。在细胞内多胺储备不足的情况下，多胺转运系统为杜氏利什曼原虫前鞭毛体提供了多胺的替代来源。
