Oxidation of L-thiazolidine-4-carboxylate by Δ1-pyrroline-5-carboxylate reductase in Escherichia coli
Oxidation of L-thiazolidine-4-carboxylate by Δ1-pyrroline-5-carboxylate reductase in Escherichia coli
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DOI：
10.1007/s002840010245
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发表时间：
2001-06-01
影响因子：
2.6
通讯作者：
Ricciardi, DL
中科院分区：
文献类型：
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作者：
Deutch, CE;Klarstrom, JL;Ricciardi, DL
l -噻唑烷-4-羧酸盐（T4C, thiaproline）是一种含硫脯氨酸类似物，可以刺激衰老小鼠的免疫系统，抑制大肠杆菌等尿路病原体。在缺乏l -脯氨酸脱氢酶的大肠杆菌putA::Tn5突变体的可溶部分中检测到NADP（+）依赖性T4C脱氢酶活性，该突变体通过硫酸铵沉淀、Cibacron Blue 3GA琼脂糖染料亲和层析和deae纤维素离子交换层析进行部分纯化。在纯化的每一步，T4C脱氢酶活性与δ(1)-吡啶-5-羧酸（P5C）还原酶活性共纯化。由于proC突变导致P5C还原酶活性大幅降低的大肠杆菌菌株没有检测到T4C脱氢酶活性。虽然P5C还原酶不作用于脯氨酸，但它也催化了3,4-脱氢脯氨酸的氧化。这些结果表明，这种生物合成酶可能在脯氨酸类似物的降解中起作用，并限制了这些化合物的临床疗效。
L-Thiazolidine-4-carboxylate (T4C, thiaproline) is a sulfur-containing proline analog that stimulates the immune system in aging mice and inhibits urinary tract pathogens such as Escherichia coli. A constitutive NADP(+)-dependent T4C dehydrogenase activity was detected in the soluble fraction of a putA::Tn5 mutant of E. coli lacking L-proline dehydrogenase and partially purified by ammonium sulfate precipitation, dye-affinity chromatography on Cibacron Blue 3GA agarose, and ion-exchange chromatography on DEAE-cellulose. At each step in the purification, T4C dehydrogenase activity copurified with Delta (1)-pyrroline-5-carboxylate (P5C) reductase activity. E. coli strains with greatly reduced P5C reductase activity due to a proC mutation had no detectable T4C dehydrogenase activity. Although P5C reductase did not act on proline, it also catalyzed the oxidation of 3,4-dehydroproline. These results suggest that this biosynthetic enzyme may play a role in the degradation of proline analogs and limit the clinical efficacy of these compounds.