The ionizing groups at the active site of alkaline phosphatase （ALP, EC 3.1.3.1） from Ostrea cucullate were studied using kinetic methods. The ionization constant, pKe, of the ionizing groups at the active site of t...The ionizing groups at the active site of alkaline phosphatase （ALP, EC 3.1.3.1） from Ostrea cucullate were studied using kinetic methods. The ionization constant, pKe, of the ionizing groups at the active site of the enzyme was found to be 10.11 at 37.0℃ and the organic solvent, dioxin, had no effect on the pKe. The standard dissociation enthalpy （△Hρ） was determined to be 10.57 kcal/mol （1 ca1=4.18 J）. The results show that the dissociation group of the enzyme active center is the ε-NH3^＋ of lysine. Chemical modification of the enzyme by acetic anhydride and succinic anhydride demonstrates that the amino group is one of the enzyme＇s functional groups.展开更多
The emergence of high-temperature superconductivity in hydrogen-rich compounds has opened up promising avenues for investigating unique hydrogen motifs that exhibit exceptional superconducting properties.Nevertheless,...The emergence of high-temperature superconductivity in hydrogen-rich compounds has opened up promising avenues for investigating unique hydrogen motifs that exhibit exceptional superconducting properties.Nevertheless,the requirement for extremely high synthesis pressures poses significant barriers to experimentally probing potential physical properties.Here,we have designed a structure wherein NH_(3)tetrahedra are intercalated into the body-centered cubic lattice of Yb,resulting in the formation of Yb(NH_(3))_(4).Our first-principles calculations reveal that metallic behavior emerges from the ionization of sp^(3)-hybridized s-bonds in NH_(3),which is enabled by electron transfer from ytterbium orbitals to NH_(3)anti-bonding s-orbitals.A distinctive feature of this structure is the Fermi surface nesting,which leads to optical phonon softening and consequently enhances electron-phonon coupling.The subsequent density-functional theory(DFT)calculations demonstrate that this I-43m phase of Yb(NH_(3))4 exhibits a superconducting critical temperature(T_(c))of 17.32 K under a modest pressure of 10 GPa.Our investigation presents perspectives on achieving phonon-mediated superconductivity at relatively low pressures,thereby opening up extensive possibilities for the attainment of high-temperature superconductivity in hydrogen-based superconducting systems with specific ionized molecular groups.展开更多
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the Ministry of Education, China
文摘The ionizing groups at the active site of alkaline phosphatase （ALP, EC 3.1.3.1） from Ostrea cucullate were studied using kinetic methods. The ionization constant, pKe, of the ionizing groups at the active site of the enzyme was found to be 10.11 at 37.0℃ and the organic solvent, dioxin, had no effect on the pKe. The standard dissociation enthalpy （△Hρ） was determined to be 10.57 kcal/mol （1 ca1=4.18 J）. The results show that the dissociation group of the enzyme active center is the ε-NH3^＋ of lysine. Chemical modification of the enzyme by acetic anhydride and succinic anhydride demonstrates that the amino group is one of the enzyme＇s functional groups.
基金work was supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406200 and 2022YFA1405500)the National Natural Science Foundation of China(Grant Nos.12304021 and 52072188)+4 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ23A040004)Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)the Natural Science Foundation of Ningbo(Grant No.2022J091)the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT 15R23)Parts of calculations were performed at the Supercomputer Center of Ningbo University.
文摘The emergence of high-temperature superconductivity in hydrogen-rich compounds has opened up promising avenues for investigating unique hydrogen motifs that exhibit exceptional superconducting properties.Nevertheless,the requirement for extremely high synthesis pressures poses significant barriers to experimentally probing potential physical properties.Here,we have designed a structure wherein NH_(3)tetrahedra are intercalated into the body-centered cubic lattice of Yb,resulting in the formation of Yb(NH_(3))_(4).Our first-principles calculations reveal that metallic behavior emerges from the ionization of sp^(3)-hybridized s-bonds in NH_(3),which is enabled by electron transfer from ytterbium orbitals to NH_(3)anti-bonding s-orbitals.A distinctive feature of this structure is the Fermi surface nesting,which leads to optical phonon softening and consequently enhances electron-phonon coupling.The subsequent density-functional theory(DFT)calculations demonstrate that this I-43m phase of Yb(NH_(3))4 exhibits a superconducting critical temperature(T_(c))of 17.32 K under a modest pressure of 10 GPa.Our investigation presents perspectives on achieving phonon-mediated superconductivity at relatively low pressures,thereby opening up extensive possibilities for the attainment of high-temperature superconductivity in hydrogen-based superconducting systems with specific ionized molecular groups.
