热带利什曼原虫前鞭毛体中α-氨基异丁酸摄取系统的特征

Characteristics of an uptake system for alpha-aminoisobutyric acid in Leishmania tropica promastigotes.

作者信息

Lepley P R, Mukkada A J

出版信息

J Protozool. 1983 Feb;30(1):41-6. doi: 10.1111/j.1550-7408.1983.tb01030.x.

DOI:10.1111/j.1550-7408.1983.tb01030.x

Abstract

Leishmania tropica promastigotes transport alpha-aminoisobutyric acid (AIB), the nonmetabolizable analog of neutral amino acids, against a substantial concentration gradient. AIB is not incorporated into cellular material but accumulates within the cells in an unaltered form. Intracellular AIB exchanges with external AIB. Various energy inhibitors (amytal, HOQNO, KCN, DNP, CCCP, and arsenate) and sulfhydryl reagents (NEM, pCMB, and iodoacetate) severely inhibit uptake. The uptake system is saturable with reference to AIB and the Lineweaver-Burk plots show biphasic kinetics suggesting the involvement of two transport systems. AIB shares a common transport system with alanine, cysteine, glycine, methionine, serine, and proline. Uptake is regulated by feedback inhibition and transinhibition.

摘要

热带利什曼原虫前鞭毛体逆着显著的浓度梯度转运α-氨基异丁酸（AIB），AIB是中性氨基酸的非代谢类似物。AIB不会掺入细胞物质中，而是以未改变的形式在细胞内积累。细胞内的AIB与细胞外的AIB进行交换。各种能量抑制剂（戊巴比妥、羟基喹啉-N-氧化物、氰化钾、二硝基苯酚、羰基氰化物间氯苯腙和砷酸盐）和巯基试剂（N-乙基马来酰胺、对氯汞苯甲酸和碘乙酸）会严重抑制摄取。摄取系统相对于AIB是可饱和的，Lineweaver-Burk图显示双相动力学，提示涉及两个转运系统。AIB与丙氨酸、半胱氨酸、甘氨酸、蛋氨酸、丝氨酸和脯氨酸共用一个共同的转运系统。摄取受反馈抑制和反抑制调节。