由于氨基脲敏感胺氧化酶在肥胖和糖尿病患者中活性显著升高，其抑制剂的开发一直是研究热点，不过，目前还缺乏天然、安全、有效的抑制剂。我们的前期研究结果表明，咖啡因在体外和体内可以抑制SSAO酶活性，并显著降低大鼠血清中甘油三酯的含量，但是其分子机制尚不清楚。本项目提出一个新假说，咖啡因通过抑制SSAO酶活，减少脂肪细胞对葡萄糖的摄取，最终抑制脂肪合成。为了检验该假说，拟开展三方面内容：①采用质谱法、计算机分子对接技术和酶活测定法系统研究咖啡因抑制SSAO酶的机理；②针对脂肪合成代谢途径上的关键蛋白质（群）设计QconCAT，发展定量肽段串联体蛋白质结合多反应监测的绝对定量方法；③建立细胞模型，探索不同时间小鼠脂肪细胞中SSAO活性、含量与咖啡因含量的规律，用QconCAT定量方法研究脂肪合成代谢途径上蛋白质绝对丰度的动态变化，阐明咖啡因抑制脂肪合成的分子机制。

The research and development of SSAO inhibitors is a hot field since the activity of semicarbazide-sensitive amine oxidase was significantly higher in obese and diabetic patients. However, there are no natural, safe and effective inhibitors so far. Our preliminary results showed that caffeine can inhibit SSAO activity both in vitro and in vivo and significantly lower triglyceride levels in rats’ serum, but the molecular mechanism is not clear. We propose a new hypothesis that caffeine can inhibit SSAO activity, reduce glucose uptake in fat cells and ultimately block fat synthesis. To test this hypothesis, the project plans to carry out three aspects: The interaction between the caffeine and SSAO is investigated by mass spectrometry, computer molecular docking and SSAO enzyme activity assay; the absolute quantification assay (Concatamers of Q peptides, QconCAT coupled with multiple reaction monitoring ) is developed to quantify the key proteins in fat synthesis pathway; SSAO activity, SSAO abundance and caffeine content are investigated in the adipocytes at different time. The protein dynamics in fat synthesis pathway is explored by QconCAT assay to elucidate the molecular mechanisms of blocking fat synthesis by caffeine.