A new crystalline form of carboxypeptidase A (CPA) complexes withan inactivator was obtained by the method of hanging drop vapor diffusion. The inacti-’vator, 2-benzyl-3-iodo-propanoic acid (BIPA ), binds covalently ...A new crystalline form of carboxypeptidase A (CPA) complexes withan inactivator was obtained by the method of hanging drop vapor diffusion. The inacti-’vator, 2-benzyl-3-iodo-propanoic acid (BIPA ), binds covalently to an active siteresidue Glu-27O of CPA. The complex was crystallized in space group P212121 with a= 48. 8 A, b=66. 9 A, c= 96. 0 A. The complex structure was determined by molecu-lar replacement using the native CPA crystal structure as the search model. The finalcrystallographic residual is 0. 152. Except for the modification of Glu-270, the inactiva-tor exhibits normal binding mode compared with other ligand complexes of CPA. Inthe final different electron density maps (2Fo-Fc, Fo-Fc), the density of the iodo ioncould not be found while the conserved molecule remains coordinated to Zn2+ as in thenative CPA. Comparisons of complex of CPA-BIPA with the native CPA and theCPA/D-Phe complex are presented. The mechanism of inactivation of CPA was dis-cussed.展开更多
Transition-metal catalyzed cross-coupling is one of the basic strategies for the C-C bond formation.However,it is difficult to achieve satisfactory results when terminal alkynes with electron-withdrawing group such as...Transition-metal catalyzed cross-coupling is one of the basic strategies for the C-C bond formation.However,it is difficult to achieve satisfactory results when terminal alkynes with electron-withdrawing group such as propiolate esters are used.The reason behind this might be the easy polymerization of this type of alkynes in the presence of base.A tetrahydroxydiboron and copper sulfate co-promoted cross-coupling/cyclization of propiolate esters and o-iodobenzoic acid for the facile and efficient construction of phthalides is described.Preliminary mechanism study indicates that tetrahydroxydiboron can inhibit the polymerization of propiolate esters and increase the reaction rate.This method is characterized by high regio-and stereoselectivities,mild reaction conditions,short reaction time,broad substrate scope,and excellent functional group compatibility.展开更多
文摘A new crystalline form of carboxypeptidase A (CPA) complexes withan inactivator was obtained by the method of hanging drop vapor diffusion. The inacti-’vator, 2-benzyl-3-iodo-propanoic acid (BIPA ), binds covalently to an active siteresidue Glu-27O of CPA. The complex was crystallized in space group P212121 with a= 48. 8 A, b=66. 9 A, c= 96. 0 A. The complex structure was determined by molecu-lar replacement using the native CPA crystal structure as the search model. The finalcrystallographic residual is 0. 152. Except for the modification of Glu-270, the inactiva-tor exhibits normal binding mode compared with other ligand complexes of CPA. Inthe final different electron density maps (2Fo-Fc, Fo-Fc), the density of the iodo ioncould not be found while the conserved molecule remains coordinated to Zn2+ as in thenative CPA. Comparisons of complex of CPA-BIPA with the native CPA and theCPA/D-Phe complex are presented. The mechanism of inactivation of CPA was dis-cussed.
基金Project supported by the National Natural Science Foundation of China(No.22271214)。
文摘Transition-metal catalyzed cross-coupling is one of the basic strategies for the C-C bond formation.However,it is difficult to achieve satisfactory results when terminal alkynes with electron-withdrawing group such as propiolate esters are used.The reason behind this might be the easy polymerization of this type of alkynes in the presence of base.A tetrahydroxydiboron and copper sulfate co-promoted cross-coupling/cyclization of propiolate esters and o-iodobenzoic acid for the facile and efficient construction of phthalides is described.Preliminary mechanism study indicates that tetrahydroxydiboron can inhibit the polymerization of propiolate esters and increase the reaction rate.This method is characterized by high regio-and stereoselectivities,mild reaction conditions,short reaction time,broad substrate scope,and excellent functional group compatibility.
