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首页> 外文期刊>Journal of bacteriology >Methylamine and ammonia transport in Saccharomyces cerevisiae.
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Methylamine and ammonia transport in Saccharomyces cerevisiae.

机译：酿酒酵母中的甲胺和氨气运输。

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Methylamine (methylammonium ion) entered Saccharomyces cerevisiae X2180-A by means of a specific active transport system. Methylamine uptake was pH dependent (maximum rate between pH 6.0 and 6.5) and temperature dependent (increasing up to 35 C) and required the presence of a fermentable or oxidizable energy source in the growth medium. At 23 C the vmax for methylamine transport was similar 17 nmol/min per mg of cells (dry weight) and the apparent Km was 220 muM. The transport system exhibited maximal activity in ammonia-grown cells and was repressed 60 to 70 percent when glutamine or asparagine was added to the growth medium. There was no significant derepression of the transport system during nitrogen starvation. Ammonia (ammonium ion) was a strong competitive inhibitor of methylamine uptake, whereas other amines inhibited to a much lesser extent. Mutants selected on the basis of their reduced ability to transport methylamine (Mea-R) simultaneously exhibited a decreased ability to transport ammonia.
机译：甲胺（甲基铵离子）通过特定的主动转运系统进入酿酒酵母X2180-A。甲胺的吸收取决于pH（最大速率在6.0和6.5之间）和温度（取决于35 C），并且需要在生长培养基中存在可发酵或可氧化的能源。在23°C下，甲胺转运的vmax约为17 nmol / min / mg细胞（干重），表观Km为220μM。该运输系统在氨生长的细胞中表现出最大的活性，当向生长培养基中添加谷氨酰胺或天冬酰胺时，该运输系统被抑制60％至70％。在氮饥饿期间，运输系统没有明显的抑制。氨（铵离子）是甲胺吸收的强竞争抑制剂，而其他胺的抑制作用要小得多。根据其降低的甲胺转运能力（Mea-R）选择的突变体同时显示出降低的氨转运能力。

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