Soluble invertase was purified from pea （Pisum sativum L.） by sequential procedures entailing ammonium sulfate precipitation, DEAE-Sepharose column, Con-A- and Green 19-Sepharose affinity columns, hydroxyapatite col...Soluble invertase was purified from pea （Pisum sativum L.） by sequential procedures entailing ammonium sulfate precipitation, DEAE-Sepharose column, Con-A- and Green 19-Sepharose affinity columns, hydroxyapatite column, ultra-filtration, and Sephacryl 300 gel filtration. The purified soluble acid （SAC） and alkaline （SALK） invertases had a pH optimum of 5.3 and 7.3, respectively. The temperature optimum of two invertases was 37 ℃. The effects of various concentrations of Tris-HCI, HgCI2, and CuSO4 on the activities of the two purified enzymes were examined. Tris-HCI and HgCI2 did not affect SAC activity, whereas 10 mM Tris-HCI and 0.05 mM HgCI2 inhibited SALK activity by about 50%. SAC and SALK were inhibited by 4.8 mM and 0.6 mM CuSO4 by 50%, respectively. The enzymes display typical hyperbolic saturation kinetics for sucrose hydrolysis. The Kms of SAC and SALK were determined to be 1.8 and 38.6 mM, respectively. The molecular masses of SAC shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting were 22 kDa and 45 kDa. The molecular mass of SALK was 30 kDa. Iso-electric points of the SAC and SALK were estimated to be about pH 7.0 and pH 5.7, respectively.展开更多
Surface regulating the electronic structure and d-band center of electrocatalysts is very much crucial to improving their alkaline hydrogen evolution reaction(HER)performance.Herein,we combined density functional theo...Surface regulating the electronic structure and d-band center of electrocatalysts is very much crucial to improving their alkaline hydrogen evolution reaction(HER)performance.Herein,we combined density functional theory(DFT)computations and experimental studies to prepare and study single transition metal-doped Ni_(3)N nanosheets combined on Ni foam(M-Ni_(3)N,M=V,Cr,Mn,W,Mo,Co and Fe)for ultra-efficient alkaline hydrogen evolution.Physicochemical characterization of as-synthesized M-Ni_(3)N demonstrated that the electrons transferred and aggregated on the catalyst surface,which resulted in their unique electronic structure and chemical composition.DFT computations demonstrated that downshifting of the d-band center weakened the adsorption energy of hydrogen and transition metal doping directly facilitated the adsorption of H_(2)O on M sites(desorption of H on Ni sites)at the surface of M-Ni_(3)N.As a result,a heterolytic cleavage process of water on M-Ni_(3)N nanosheets was formulated,thus drastically boosting the alkaline HER.Specifically,as the best example,the fabricated V-doped Ni_(3)N catalyst exhibited remarkable alkaline HER performance with significantly low overpotential of only 15 mV at a current density of 10 mA cm−2.The strategy exemplified in this work provides a useful way to rational design for highly efficient hydrogen evolution reaction electrocatalysts.展开更多
基金supported by grants from the Korea Ocean Research & Development Institute (PE98474)by grants from BioGreen 21 Project funded by Rural Development Administration of Korea (20070401-034-028-009)
文摘Soluble invertase was purified from pea （Pisum sativum L.） by sequential procedures entailing ammonium sulfate precipitation, DEAE-Sepharose column, Con-A- and Green 19-Sepharose affinity columns, hydroxyapatite column, ultra-filtration, and Sephacryl 300 gel filtration. The purified soluble acid （SAC） and alkaline （SALK） invertases had a pH optimum of 5.3 and 7.3, respectively. The temperature optimum of two invertases was 37 ℃. The effects of various concentrations of Tris-HCI, HgCI2, and CuSO4 on the activities of the two purified enzymes were examined. Tris-HCI and HgCI2 did not affect SAC activity, whereas 10 mM Tris-HCI and 0.05 mM HgCI2 inhibited SALK activity by about 50%. SAC and SALK were inhibited by 4.8 mM and 0.6 mM CuSO4 by 50%, respectively. The enzymes display typical hyperbolic saturation kinetics for sucrose hydrolysis. The Kms of SAC and SALK were determined to be 1.8 and 38.6 mM, respectively. The molecular masses of SAC shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting were 22 kDa and 45 kDa. The molecular mass of SALK was 30 kDa. Iso-electric points of the SAC and SALK were estimated to be about pH 7.0 and pH 5.7, respectively.
基金the National Natural Science Foundation of China(52222408)MCC Changtian Scientific Research and Development Basic Research Fund(2022JCYJ04)the Ministry of Education’s Industry School Cooperation Collaborative Education Project and Shandong Shandong Weiqiao Pioneering Group Co.,Ltd(220506429071743)for their financial support.
文摘Surface regulating the electronic structure and d-band center of electrocatalysts is very much crucial to improving their alkaline hydrogen evolution reaction(HER)performance.Herein,we combined density functional theory(DFT)computations and experimental studies to prepare and study single transition metal-doped Ni_(3)N nanosheets combined on Ni foam(M-Ni_(3)N,M=V,Cr,Mn,W,Mo,Co and Fe)for ultra-efficient alkaline hydrogen evolution.Physicochemical characterization of as-synthesized M-Ni_(3)N demonstrated that the electrons transferred and aggregated on the catalyst surface,which resulted in their unique electronic structure and chemical composition.DFT computations demonstrated that downshifting of the d-band center weakened the adsorption energy of hydrogen and transition metal doping directly facilitated the adsorption of H_(2)O on M sites(desorption of H on Ni sites)at the surface of M-Ni_(3)N.As a result,a heterolytic cleavage process of water on M-Ni_(3)N nanosheets was formulated,thus drastically boosting the alkaline HER.Specifically,as the best example,the fabricated V-doped Ni_(3)N catalyst exhibited remarkable alkaline HER performance with significantly low overpotential of only 15 mV at a current density of 10 mA cm−2.The strategy exemplified in this work provides a useful way to rational design for highly efficient hydrogen evolution reaction electrocatalysts.
