Molecular mechanism of the inhibitory effect of methylation outside the recognition sequence of restriction endonuclease Pvu Π on its cleavage activity

In 1991, we found that methylation outside the PvuⅡ recognition sequence could partially inhibit its cleavage activity. To clarify the molecular mechanism, three plasmids with different methylation states were constructed. Then, together with the original one, four plasmids were digested with different amounts of PvuⅡ. Results show that methylation on both sites results in 90% inhibition; moving the methylated site one base further away decreases the inhibitory effect to about 30%; with the adjacent dam methylation site eliminated, the inhibitory effect disappears. The data suggest that the inhibition of cleavage activity caused by outside methylation is not "all or none", and the degree of inhibition is dependent on the position and the number of methylated bases.     

基于网络药理学方法的黄芩现代药理活性挖掘及其作用机制分析

采用高效液相色谱-电喷雾-四级杆-飞行时间质谱仪对黄芩水煎液中化学成分进行识别,发现水煎液中主要含有8种黄酮类成分。进一步采用网络药理学方法对8种化合物可能的作用靶点及其相关疾病进行了预测,发现黄芩除了与已报道的抗炎、抗肿瘤等疾病相关,还与水肿、中毒、高血压、出血、心脏病等多种疾病相关,这与黄芩传统功效的泻火解毒、止血的功效相近。通过通路富集分析,发现黄芩可能主要是通过调节代谢通路、脂肪细胞代谢通路、花生四烯酸代谢、5-羟色胺突触、精氨酸生物合成、钙离子信号通路发挥其多重药理活性。研究表明,网络药理学研究方法可为中药传统功效的挖掘及其药理机制研究提供新的方向。