Catabolism of leucine to branched-chain fatty acids in Staphylococcus xylosus
Catabolism of leucine to branched-chain fatty acids in Staphylococcus xylosus
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DOI：
10.1111/j.1365-2672.2004.02253.x
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发表时间：
2004-01-01
影响因子：
4
通讯作者：
Lauritsen, FR
中科院分区：
文献类型：
--
作者：
Beck, HC;Hansen, AM;Lauritsen, FR
目的：木糖葡萄球菌是发酵肉制品中由支链氨基酸亮氨酸、缬氨酸和异亮氨酸产生风味剂的重要发酵剂。感官上最重要的风味化合物是支链的醛和酸衍生自相应的氨基酸，本文打算透视这些风味化合物的背景下，亮氨酸metabolisation.Methods和结果：GC和GC/MS分析结合稳定同位素标记研究亮氨酸catabolism。这种氨基酸与缬氨酸和异亮氨酸一起被用作生长期间细胞膜生物合成的支链脂肪酸生产的前体。83.3%的细胞脂肪酸为支链脂肪酸。主要脂肪酸是antiso-C-15：0，占脂肪酸的55%。吡哆醛5 '-磷酸和α-酮酸依赖性反应催化亮氨酸、缬氨酸和异亮氨酸脱氨基成其相应的α-酮酸。作为α-氨基受体，α-酮基-β-甲基戊酸和α-酮基异戊酸比α-酮基戊二酸有效得多。3-甲基丁酸是支链脂肪酸生成途径中的关键中间体，在稳定生长期开始时由亮氨酸生成，然后，当生长培养基中的亮氨酸变得稀缺时，由葡萄糖通过丙酮酸氧化生成。本文证明了感官上重要的分支-链醛和酸是细胞膜生物合成支链脂肪酸的代谢途径上的重要中间体。研究的意义和影响：所获得的代谢信息对于未来生产发酵肉的发酵剂的生物技术设计是极其重要的。
Aims: Staphylococcus xylosus is an important starter culture in the production of flavours from the branched-chain amino acids leucine, valine and isoleucine in fermented meat products. The sensorially most important flavour compounds are the branched-chain aldehydes and acids derived from the corresponding amino acids and this paper intends to perspectivate these flavour compounds in the context of leucine metabolism.Methods and Results: GC and GC/MS analysis combined with stable isotope labelling was used to study leucine catabolism. This amino acid together with valine and isoleucine was used as precursors for the production of branched-chain fatty acids for cell membrane biosynthesis during growth. A 83.3% of the cellular fatty acids were branched. The dominating fatty acid was anteiso-C-15:0 that constituted 55% of the fatty acids. A pyridoxal 5'-phosphate and alpha-ketoacid dependent reaction catalysed the deamination of leucine, valine and isoleucine into their corresponding alpha-ketoacids. As alpha-amino group acceptor alpha-keto-beta-methylvaleric acid and alpha-ketoisovaleric acid was much more efficient than alpha-ketoglutarate. The sensorially and metabolic key intermediate on the pathway to the branched-chain fatty acids, 3-methylbutanoic acid was produced from leucine at the onset of the stationary growth phase and then, when the growth medium became scarce in leucine, from the oxidation of glucose via pyruvate.Conclusions: This paper demonstrates that the sensorially important branched-chain aldehydes and acids are important intermediates on the metabolic route leading to branched-chain fatty acids for cell membrane biosynthesis.Significance and Impact of the Study: The metabolic information obtained is extremely important in connection with a future biotechnological design of starter cultures for production of fermented meat.