Synthesis and Expression of a Gene From Kringle-2 Domain of Tissue Plasminogen Activator in E. coli

The DNA fragment corresponding to the tissue plasminogen activator (tPA) sequence 174-262 (Kringle-2 domain) has been synthesized by using the solid phase phosphotriester method. The Kringle-2 domain of human tPA was expressed in Escherichia colt by secretion into the periplasmic space using the Lpp-Lac promoter and PIN-Ⅲ OmpA2 signal sequence. About two thirds of the expression product was secreted into the periplasmic space , and purified with ammonium sulfate fractionation, affinity chro-matography on Lysine-Sepharose, and FPLC-Mono Q exchange chromatography. The amino acid composition observed from the Kringle-2 purified from E. coli is identical with that expected for the 174-262 fragment of human tPA. Radio binding assay shows that the recombinant Kringle-2 domain possesses the activity of fibrin binding.     

四氯化钛存在下芳香环氧化合物与β-萘酚的反应

在四氯化钛存在下,芳香环氧化合物和β-萘酚发生反应,生成萘并二氢呋喃和1-芳乙烯基萘酚-2。     

双戊二酮合钴催化作用的研究(Ⅲ)——α,α,α-三氯甲苯与醇的反应

过渡金属的戊二酮配合物容易制备和保存,是常用的催化剂,我们曾用双戊二酮合钻催化醚化、酯化和烃化反应,文献报道三氯甲苯(1)与无水乙醇在130～140℃反应生成苯甲酸、氯乙烷和少量苯甲酸乙酯,在氯化锌催化下1与乙醇反应生成苯甲酸乙酯,我们发现在无水双戊二酮合钴Co(acac)_2催化下,1与醇在较低的温度(100℃     

脱氢醋酸与氨的反应

脱氢醋酸(1)与氨反应生成2,6-二甲基-4-羟基吡啶(2)^[1]。IguChi等^[2]曾用纸层析法定性地研究了这反应的过程。为进一步了解(1)与氨反应的历程及影响反应的因素,我们用HPLC研究了在不同反应条件下得到的中间体和产物,研究了相互转变关系,并进行了分离和鉴定。初步提出了该反应的可能历程。