Bioavailable glutamine (Gln) is critical for metabolism, intestinal health, immune function, and cell signaling. Routine measurement of serum Gln concentrations could facilitate improved diagnosis and treatment of severe infections, anorexia nervosa, chronic kidney disease, diabetes, and cancer. Current methods for quantifying tissue Gln concentrations rely mainly on HPLC, which requires extensive sample preparation and expensive equipment. Consequently, patient Gln levels may be clinically underutilized. Cell-free protein synthesis (CFPS) is an emerging sensing platform with promising clinical applications, including detection of hormones, amino acids, nucleic acids, and other biomarkers. In this work, in vitro E. coli amino acid metabolism is engineered with methionine sulfoximine to inhibit glutamine synthetase and create a CFPS Gln sensor. The sensor features a strong signal-to-noise ratio and a detection range ideally suited to physiological Gln concentrations. Furthermore, it quantifies Gln concentration in the presence of human serum. This work demonstrates that CFPS reactions which harness the metabolic power of E. coli lysate may be engineered to detect clinically relevant analytes in human samples. This approach could lead to transformative point-of-care diagnostics and improved treatment regimens for a variety of diseases including cancer, diabetes, anorexia nervosa, chronic kidney disease, and severe infections.

生物可利用的谷氨酰胺 (Gln) 对新陈代谢、肠道健康、免疫功能和细胞信号传导至关重要。血清 Gln 浓度的常规测量有助于改善严重感染、神经性厌食症、慢性肾病、糖尿病和癌症的诊断和治疗。目前量化组织 Gln 浓度的方法主要依赖于 HPLC，这需要大量的样品制备和昂贵的设备。因此，临床上可能未充分利用患者的 Gln 水平。无细胞蛋白质合成（CFPS）是一种新兴的传感平台，具有广阔的临床应用前景，包括检测激素、氨基酸、核酸和其他生物标志物。在这项工作中，体外大肠杆菌用蛋氨酸亚砜亚胺设计氨基酸代谢以抑制谷氨酰胺合成酶并创建 CFPS Gln 传感器。该传感器具有很强的信噪比和非常适合生理 Gln 浓度的检测范围。此外，它量化了人血清存在下的 Gln 浓度。这项工作表明，可以设计利用大肠杆菌裂解物代谢能力的 CFPS 反应来检测人类样本中的临床相关分析物。这种方法可能会带来变革性的即时诊断和改进的各种疾病的治疗方案，包括癌症、糖尿病、神经性厌食症、慢性肾病和严重感染。