Speckman R A, Collins E B
Appl Microbiol. 1973 Nov;26(5):744-6. doi: 10.1128/am.26.5.744-746.1973.
Streptococcus diacetilactis was grown in a partially defined, lipoic acid-free medium containing radioactive acetate with and without addition of 0.1% unlabeled sodium pyruvate. Labeled carbon was incorporated into diacetyl, but neither the amount of diacetyl produced nor its specific activity was influenced by addition of pyruvate. Acetoin had low specific activity, indicating that it was a mixture of radioactive and nonradioactive acetoin. The specific activity of acetoin was lower when pyruvate, a precursor of unlabeled acetoin, was added to the medium, which indicated that the radioactive acetoin was produced from radioactive diacetyl by diacetyl reductase. Results substantiate condensation of acetyl-coenzyme A with hydroxyethylthiamine pyrophosphate as the in vivo mechanism for synthesis of diacetyl.
双乙酰乳链球菌在一种部分限定的、不含硫辛酸的培养基中生长，该培养基含有放射性乙酸盐，分别添加和不添加0.1%未标记的丙酮酸钠。标记的碳被整合到双乙酰中，但添加丙酮酸钠既不影响双乙酰的产量，也不影响其比活性。乙偶姻的比活性较低，表明它是放射性和非放射性乙偶姻的混合物。当将未标记乙偶姻的前体丙酮酸钠添加到培养基中时，乙偶姻的比活性较低，这表明放射性乙偶姻是由双乙酰还原酶将放射性双乙酰转化产生的。结果证实了乙酰辅酶A与焦磷酸羟乙基硫胺素缩合是体内合成双乙酰的机制。
