Yarlett N, Bacchi C J
Haskins Laboratories and Biology Department, Pace University, New York, NY 10038.
Mol Biochem Parasitol. 1988 Oct;31(1):1-9. doi: 10.1016/0166-6851(88)90139-9.
Growth of Trichomonas vaginalis in a semi-defined medium was inhibited by 5 mM DL-alpha-difluoromethylornithine (DFMO). Using high pressure liquid chromatography (HPLC) analysis, putrescine and cadaverine levels were found to be 90 and 100% reduced, respectively after 120 h exposure, whilst spermidine and spermine levels were unchanged. Putrescine (40 microM) and cadaverine (6 microM) were detected in the spent media from control cultures. Neither of these diamines was detected in spent media from 72 h DFMO-treated cultures. Changes in intracellular levels of amine precursors were also determined by HPLC. There was a transient increase in ornithine to 39 nmol (mg protein)-1 at 48 h in the DFMO-treated cells while it remained undetectable in control cells throughout the experiment. Arginine and citrulline levels remained high, decreasing to control levels only after 72 h. Only spermine (1 mM) rescued DFMO-treated cells, and this is discussed with respect to the presence of a putative spermine-specific oxidase designated by its sensitivity to aminoguanidine. Aerobic incubation of growing (normal) cells with [14C]spermine resulted in the production of an unknown metabolite (19% of total label), whose content was reduced to 5% under anaerobic conditions. Decarboxylated S-adenosylmethionine remained undetectable in DFMO-treated cells, and the methylation index (ratio of S-adenosylmethionine to S-adenosylhomocysteine) did not change from the control value of 9.3. Ornithine decarboxylase, S-adenosylmethionine synthetase, S-adenosylmethionine:L-homocysteine methyltransferase, and S-adenosylhomocysteine hydrolase enzyme activities were detected. However, S-adenosylmethionine decarboxylase, spermidine synthase or spermine synthase were not detected. These findings are discussed with reference to the arginine dihydrolase pathway whose end products are putrescine and ATP.(ABSTRACT TRUNCATED AT 250 WORDS)
5 mM DL-α-二氟甲基鸟氨酸（DFMO）可抑制阴道毛滴虫在半限定培养基中的生长。通过高压液相色谱（HPLC）分析发现，暴露120小时后，腐胺和尸胺水平分别降低了90%和100%，而亚精胺和精胺水平未变。在对照培养物的用过的培养基中检测到腐胺（40 microM）和尸胺（6 microM）。在DFMO处理72小时的培养物的用过的培养基中未检测到这两种二胺中的任何一种。胺前体的细胞内水平变化也通过HPLC测定。在DFMO处理的细胞中，鸟氨酸在48小时时短暂增加至39 nmol（mg蛋白）-1，而在整个实验过程中对照细胞中仍未检测到。精氨酸和瓜氨酸水平保持较高，仅在72小时后降至对照水平。只有精胺（1 mM）能挽救DFMO处理的细胞，这一点结合对一种假定的对氨基胍敏感的精胺特异性氧化酶的存在进行了讨论。用[14C]精胺对生长中的（正常）细胞进行需氧培养会产生一种未知代谢物（占总标记的19%），在厌氧条件下其含量降至5%。在DFMO处理的细胞中未检测到脱羧S-腺苷甲硫氨酸，甲基化指数（S-腺苷甲硫氨酸与S-腺苷同型半胱氨酸的比率）与对照值9.3相比没有变化。检测到鸟氨酸脱羧酶、S-腺苷甲硫氨酸合成酶、S-腺苷甲硫氨酸：L-同型半胱氨酸甲基转移酶和S-腺苷同型半胱氨酸水解酶的活性。然而，未检测到S-腺苷甲硫氨酸脱羧酶、亚精胺合成酶或精胺合成酶。这些发现结合以腐胺和ATP为终产物的精氨酸双水解酶途径进行了讨论。（摘要截短至250字）
