N-glycolyl chondroitin (Gc-CN) is a metabolite of N-glycolylneuraminic acid (Neu5Gc), a sialic acid that is commonly found in mammals, but not humans. Humans can incorporate exogenous Neu5Gc into their tissues from eating red meat. Neu5Gc cannot be biosynthesized by humans due to an evolutionary mutation and has been implicated in causing inflammation causing human diseases, such as cancer. The study Neu5Gc is important in evolutionary biology and the development of potential cancer biomarkers. Unfortunately, there are several limitations to detecting Neu5Gc. The elimination of Neu5Gc involves a degradative pathway leading to the incorporation of N-glycolyl groups into glycosaminoglycans (GAGs), such as Gc-CN. Gc-CN has been found in humans and in animals including mice, lamb and chimpanzees. Here, we present the biosynthesis of Gc-CN in bacteria by feeding chemically synthesized N-glycolylglucosamine to Escherichia coli. A metabolically engineered strain of E. coli K4, fed with glucose supplemented with GlcNGc, converted it to N-glycolylgalactosamine (GalNGc) that could then be utilized as a substrate in the chondroitin biosynthetic pathway. The final product, Gc-CN was converted to disaccharides using chondroitin lyase ABC and analyzed by liquid chromatography–tandem mass spectrometry with multiple reaction monitoring detection. This analysis showed the incorporation of GalNGc into the backbone of the chondroitin oligosaccharide.

中文翻译：

---

使用代谢工程化的大肠杆菌合成N-羟乙酸软骨素。

Ñ -glycolyl软骨素（GC-CN）是的代谢物ñ -羟乙酰神经氨酸（Neu5Gc的），唾液酸是通常在哺乳动物中发现的，而不是人类。人类可以通过食用红肉将外源性Neu5Gc整合到他们的组织中。由于进化突变，Neu5Gc不能由人类生物合成，并且与引起炎症等人类疾病（如癌症）有关。Neu5Gc的研究在进化生物学和潜在癌症生物标记物的开发中很重要。不幸的是，检测Neu5Gc有一些限制。Neu5Gc的消除涉及导致N结合的降解途径-糖醇基转化为糖胺聚糖（GAG），例如Gc-CN。已在人和动物（包括小鼠，羔羊和黑猩猩）中发现了Gc-CN。在这里，我们介绍了通过将化学合成的N-乙二醇基葡萄糖胺喂入大肠杆菌，在细菌中进行Gc-CN的生物合成。喂食补充有GlcNGc的葡萄糖的E. coli K4代谢工程菌株，将其转化为N-糖基半乳糖胺（GalNGc），可用作软骨素生物合成途径的底物。使用软骨素裂解酶ABC将最终产物Gc-CN转化为二糖，并通过液相色谱-串联质谱分析和多反应监测检测进行分析。该分析表明GalNGc掺入软骨素寡糖的主链中。