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Appl Microbiol Biotechnol. 2012 Feb;93(4):1673-83. doi: 10.1007/s00253-011-3500-3. Epub 2011 Aug 21.
Despite their importance as potent odors that contribute to the aroma of numerous cheeses, S-methyl thioesters formation pathways have not been fully established yet. In a first part of our work, we demonstrated that Brevibacterium antiquum and Brevibacterium aurantiacum could produce S-methyl thioesters using short-chain fatty acids or branched-chain amino acids as precursors. Then, we focused our work on L-leucine catabolism using liquid chromatography tandem mass spectrometry and gas chromatography-mass spectrometry analyses coupled with tracing experiments. For the first time, several acyl-CoAs intermediates of the L-leucine to thioesters conversion pathway were identified. S-methyl thioisovalerate was produced from L-leucine, indicating that this amino acid was initially transaminated. Quite interestingly, data also showed that other S-methyl thioesters, e.g., S-methyl thioacetate or S-methyl thioisobutyrate, were produced from L-leucine. Enzymatic and tracing experiments allowed for postulating catabolic pathways leading to S-methyl thioesters biosynthesis.
尽管 S-甲基硫酯是许多奶酪香气的重要组成部分，但它们的形成途径尚未完全确定。在我们工作的第一部分中，我们证明了 Brevibacterium antiquum 和 Brevibacterium aurantiacum 可以使用短链脂肪酸或支链氨基酸作为前体来生产 S-甲基硫酯。然后，我们专注于使用液相色谱串联质谱和气相色谱-质谱分析以及示踪实验来研究 L-亮氨酸的代谢。我们首次鉴定了 L-亮氨酸向硫酯转化途径中的几种酰基辅酶 A 中间体。S-甲基硫代异戊酸酯是由 L-亮氨酸产生的，这表明这种氨基酸最初被转氨。有趣的是，数据还表明，其他 S-甲基硫酯，例如 S-甲基硫代乙酸酯或 S-甲基硫代异丁酸酯，也可以由 L-亮氨酸产生。酶和示踪实验可以推测出导致 S-甲基硫酯生物合成的代谢途径。
