UREIDOSUCCINIC ACID PERMEATION IN SACCHAROMYCES-CEREVISIAE
UREIDOSUCCINIC ACID PERMEATION IN SACCHAROMYCES-CEREVISIAE
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DOI：
10.1016/0005-2736(77)90362-5
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
LACROUTE, F
中科院分区：
文献类型：
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作者：
GRETH, ML;CHEVALLIER, MR;LACROUTE, F
一些菌株的S.酿酒酵母表现出脲基琥珀酸的特异性运输系统，其受N代谢调节。尿素琥珀酸的吸收发生与脯氨酸，但与硫酸铵作为N源，它被抑制。运输的V [速度]为每分钟20-25 μ mol/ml细胞水。表观Km为3。10-5 M.对于urep 1突变体（脲基琥珀酸通透酶较少），内部浓度从未超过外部浓度。在通透酶+菌株中，脲基琥珀酸被浓缩至10，000倍，并且积累的化合物在细胞中保持不变。能量毒物如二硝基苯酚、羰腈-间氯苯腙（CCCP）或NaN 3抑制摄取。即使在这些药物存在下，也不会发生累积化合物的显著外排。通透酶的特异性是非常严格的，只有携带α-氨基酸的氨基酸才具有这种特异性。N-氨基甲酰基是强竞争性抑制剂。细胞的高浓缩能力和缺乏累积化合物的主动排出支持载体介导的主动转运系统的假设。
Some strains of S. cerevisiae exhibit a specific transport system for ureidosuccinic acid, which is regulated by N metabolism. Ureidosuccinic acid uptake occurs with proline, but with ammonium sulfate as N source it is inhibited. The V [velocity] for transport is 20-25 .mu.mol/ml cell water per min. The apparent Km is 3 .cntdot. 10-5 M. For the urep1 mutant (ureidosuccinic acid permease less) the internal concentration never exceeds the external one. In the permease plus strain ureidosuccinic acid was concentrated up to 10,000-fold and the accumulated compound remained unchanged in the cells. Energy poisons such as dinitrophenol, carbonyl cyanide-m-chlorophenylhydrazone (CCCP) or NaN3 inhibit the uptake. No significant efflux of the accumulated compound occurs even in the presence of these drugs. The specificity of the permease is very strict, only amino acids carrying an .alpha.-N-carbamyl group are strongly competitive inhibitors. The high concentration capacity of the cells and the lack of active exit of the accumulated compound support the hypothesis of a carrier mediated active transport system.