Pyrazines are typically formed from amino acids and sugars in chemical reactions such as the Maillard reaction. In this study, we demonstrate that 3-ethyl-2,5-dimethylpyrazine can be produced from L-Thr by a simple bacterial operon. We conclude that EDMP is synthesized chemoenzymatically from L-Thr via the condensation reaction of two molecules of aminoacetone and one molecule of acetaldehyde. Aminoacetone is supplied by L-threonine 3-dehydrogenase using L-Thr as a substrate via 2-amino-3-ketobutyrate. Acetaldehyde is supplied by 2-amino-3-ketobutyrate CoA ligase bearing threonine aldolase activity from L-Thr when CoA was at low concentrations. Considering the rate of EDMP production, the reaction intermediate is stable for a certain time, and moderate reaction temperature is important for the synthesis of EDMP. When the precursor was supplied from L-Thr by these enzymes, the yield of EDMP was increased up to 20.2%. Furthermore, we demonstrate that this reaction is useful for synthesizing various alkylpyrazines.

吡嗪通常由氨基酸和糖在化学反应（例如美拉德反应）中形成。在这项研究中，我们证明可以通过简单的细菌操纵子从 L-Thr 生产 3-乙基-2,5-二甲基吡嗪。我们得出结论，EDMP 是由 L-Thr 通过两分子氨基丙酮和一分子乙醛的缩合反应以化学酶法合成的。氨基丙酮由 L-苏氨酸 3-脱氢酶使用 L-Thr 作为底物通过 2-氨基-3-酮丁酸提供。当 CoA 浓度较低时，乙醛由具有苏氨酸醛缩酶活性的 2-氨基-3-酮丁酸 CoA 连接酶从 L-Thr 提供。考虑到EDMP的产率，反应中间体在一定时间内稳定，适度的反应温度对于EDMP的合成很重要。当这些酶从L-Thr提供前体时，EDMP的产率增加至20.2%。此外，我们证明该反应可用于合成各种烷基吡嗪。