OBJECTIVE: To investigate the response of multiple myeloma (MM) cells to arsenic trioxide (As2O3) and their possible mechanisms. METHODS: Two MM-derived cell lines RPMI8226 and U266 cells were used as in vitro models....OBJECTIVE: To investigate the response of multiple myeloma (MM) cells to arsenic trioxide (As2O3) and their possible mechanisms. METHODS: Two MM-derived cell lines RPMI8226 and U266 cells were used as in vitro models. Cell apoptosis was assessed by morphology, flow cytometry, and DNA gel electrophoresis. Mitochondrial transmembrane potentials (delta psi m) were evaluated by measuring cellular Rhodamine 123 staining intensity. Protein expression was analyzed using Western blot. RESULTS: Zero point one to 0.5 mumol/L As2O3 inhibited cell proliferation and 2.0 mumol/L As2O3 induced cell apoptosis, while 1.0 mumol/L As2O3 inhibited proliferation with a weak degree of apoptosis induction in RPMI8226 and U266 cell lines. As2O3-induced apoptosis was accompanied by mitochondrial transmembrane potentials (delta psi m) collapse and caspase-3 activation in the presence of intact membrane. Glutathione depleter buthionine sulfoximine enhanced, while disulfide bond-reducing agent dithiothreitol partially antagonized As2O3-induced delta psi m collapse and apoptosis in MM cells. All-trans retinoic acid (ATRA) could also induce apoptosis in RPMI8226 cells, but it did not show any cooperative effects with As2O3. CONCLUSION: As2O3 exerts apoptosis-inducing and growth-inhibiting effects on MM cells, and mitochondrium is a pivotal and common target of As2O3 for apoptosis induction.展开更多
Soil phosphomonoesterase plays a critical role in controlling phosphorus(P) cycling for crop nutrition,especially in P-deficient soils.A 6-year field experiment was conducted to evaluate soil phosphomonoesterase activ...Soil phosphomonoesterase plays a critical role in controlling phosphorus(P) cycling for crop nutrition,especially in P-deficient soils.A 6-year field experiment was conducted to evaluate soil phosphomonoesterase activities,kinetics and thermodynamics during rice growth stages after consistent swine manure application,to understand the impacts of swine manure amendment rates on soil chemical and enzymatic properties,and to investigate the correlations between soil enzymatic and chemical variables.The experiment was set out in a randomized complete block design with three replicates and five treatments including three swine manure rates(26,39,and 52 kg P ha^(-1),representing low,middle,and high application rates,respectively) and two controls(no-fertilizer and superphosphate at 26 kg P ha^(-1)).The results indicated that the grain yield and soil chemical properties were significantly improved with the application of P-based swine manure from 0 to 39 kg P ha^(-1);however,the differences between the 39(M_(39)) and 52 kg P ha^(-1) treatments(M_(52)) were not significant.The enzymatic property analysis indicated that acid phosphomonoesterase was the predominant phosphomonoesterase in the tested soil.The M_(39) and M_(52) treatments had relatively high initial velocity(V_0),maximal velocity(V_(max)),and activation grade(lgN_a) but low Michaelis constant(K_m),temperature coefficient(Q_(10)),activation energy(E_a),and activation enthalpy(ΔH),implying that the M_(39) and M_(52) treatments could stimulate the enzyme-catalyzed reactions more easily than all other treatments.The correlation analysis showed that the distribution of soil phosphomonoesterase activities mainly followed the distributions of total C and total N.Based on these results,39 kg P ha^(-1) could be recommended as the most appropriate rate of swine manure amendment.展开更多
Selective and temporal control over protein activity is of great importance for the advancement of the protein of interest into precise molecular medicine.Simply installing synthetic ligands to proteins for activity r...Selective and temporal control over protein activity is of great importance for the advancement of the protein of interest into precise molecular medicine.Simply installing synthetic ligands to proteins for activity regulation,however,is often obscured by either nonspecificity or insufficient efficiency.This study reports a chemical approach in which enzymatic cascade reactions were designed for selective activation of pro-protein both in vitro and in vivo.Specifically,the system consisted of aromatic boronic-acid-modified nanoparticles,reactive oxygen species(ROS)-responsive pro-protein(RNase A-NBC),a small molecule drug,β-Lapachone(β-Lap),and strategically screened synthetic lipids,required for the assembly of the nanocomplexes.Once target-delivered into tumor cells,the reduction ofβ-Lap produces massive H2O2 in response to NAD(P)H quinone oxidoreductase 1(NQO1),a tumor-specific enzyme,which triggers further induction by selective chemical modification of ROS-responsive cytosolic protein ribonuclease A(RNase A)-NBC,thus,switching from“inert”pro-protein to active therapeutics,that ultimately prohibit tumor cell growth.Moreover,the designed enzymatic cascade activation of the pro-protein was effective in vivo,displaying superior therapeutic efficacy to either the pro-protein alone or theβ-Lap via tumor-targeted delivery and the consequent suppression of the tumor growth.As both RNase A andβ-Lap have been evaluated clinically as antitumor therapeutics,our chemical multi-step cascade methodology is,therefore,a promising strategy for selective modulation of pro-protein chemistry in the living system for fundamental investigations,favorable toward potential anticancer applications.展开更多
The cytochrome P411 enzyme is a variant of cytochrome P450_(BM3) from Bacillus megaterium whose active site is an iron porphyrin imine([Fe(Por)(NH)]^(-))specie.This specie has been reported to successfully promote the...The cytochrome P411 enzyme is a variant of cytochrome P450_(BM3) from Bacillus megaterium whose active site is an iron porphyrin imine([Fe(Por)(NH)]^(-))specie.This specie has been reported to successfully promote the primary amination of benzylic and allylic C(sp^(3))-H bonds.We employed density functional theory to study the electronic structure of the active site of P411 enzyme and the primary amination of C-H bond reaction that it catalyzes.The calculated spin densities and orbital values indicate the existence of resonance in this specie;namely,[(por)(–OH)Fe^(Ⅳ)–N^(2-)–H]^(-)↔[(por)(–OH)Fe^(Ⅲ)–N^(·-)–H]^(-).The amination of C(sp^(3))-H bonds consists of two main reaction steps:hydrogen-atom abstraction and radical recombination,and the former is demonstrated to be the rate-determining step.Furthermore,we studied the regioselectivity of the amination of primary and secondary C(sp^(3))-H bonds.Our calculations indicated that the secondary C(sp^(3))-H bonds of the substrate would be more favored for the activation by P411 enzyme.These results provide valuable information for understanding the properties and selectivity of C-H/C-N bond-activation reactions catalyzed by the P411 enzyme or other similar enzymes.展开更多
基金theNationalNaturalScienceFoundationofChina (No 39970 312andNo 39730 2 70 ) NationalOutstandingYoungScientificFoundationofC
文摘OBJECTIVE: To investigate the response of multiple myeloma (MM) cells to arsenic trioxide (As2O3) and their possible mechanisms. METHODS: Two MM-derived cell lines RPMI8226 and U266 cells were used as in vitro models. Cell apoptosis was assessed by morphology, flow cytometry, and DNA gel electrophoresis. Mitochondrial transmembrane potentials (delta psi m) were evaluated by measuring cellular Rhodamine 123 staining intensity. Protein expression was analyzed using Western blot. RESULTS: Zero point one to 0.5 mumol/L As2O3 inhibited cell proliferation and 2.0 mumol/L As2O3 induced cell apoptosis, while 1.0 mumol/L As2O3 inhibited proliferation with a weak degree of apoptosis induction in RPMI8226 and U266 cell lines. As2O3-induced apoptosis was accompanied by mitochondrial transmembrane potentials (delta psi m) collapse and caspase-3 activation in the presence of intact membrane. Glutathione depleter buthionine sulfoximine enhanced, while disulfide bond-reducing agent dithiothreitol partially antagonized As2O3-induced delta psi m collapse and apoptosis in MM cells. All-trans retinoic acid (ATRA) could also induce apoptosis in RPMI8226 cells, but it did not show any cooperative effects with As2O3. CONCLUSION: As2O3 exerts apoptosis-inducing and growth-inhibiting effects on MM cells, and mitochondrium is a pivotal and common target of As2O3 for apoptosis induction.
基金supported by the National Natural Science Foundation of China(Nos.21077088,41271314and 51008107)
文摘Soil phosphomonoesterase plays a critical role in controlling phosphorus(P) cycling for crop nutrition,especially in P-deficient soils.A 6-year field experiment was conducted to evaluate soil phosphomonoesterase activities,kinetics and thermodynamics during rice growth stages after consistent swine manure application,to understand the impacts of swine manure amendment rates on soil chemical and enzymatic properties,and to investigate the correlations between soil enzymatic and chemical variables.The experiment was set out in a randomized complete block design with three replicates and five treatments including three swine manure rates(26,39,and 52 kg P ha^(-1),representing low,middle,and high application rates,respectively) and two controls(no-fertilizer and superphosphate at 26 kg P ha^(-1)).The results indicated that the grain yield and soil chemical properties were significantly improved with the application of P-based swine manure from 0 to 39 kg P ha^(-1);however,the differences between the 39(M_(39)) and 52 kg P ha^(-1) treatments(M_(52)) were not significant.The enzymatic property analysis indicated that acid phosphomonoesterase was the predominant phosphomonoesterase in the tested soil.The M_(39) and M_(52) treatments had relatively high initial velocity(V_0),maximal velocity(V_(max)),and activation grade(lgN_a) but low Michaelis constant(K_m),temperature coefficient(Q_(10)),activation energy(E_a),and activation enthalpy(ΔH),implying that the M_(39) and M_(52) treatments could stimulate the enzyme-catalyzed reactions more easily than all other treatments.The correlation analysis showed that the distribution of soil phosphomonoesterase activities mainly followed the distributions of total C and total N.Based on these results,39 kg P ha^(-1) could be recommended as the most appropriate rate of swine manure amendment.
基金support from the National Key Research and Development Program of China(2017YFA0208100 to M.W.,2016YFA0200104 to LM)the National Science Foundation of China(21778056 to M.W.21790390 and 21790391 to L.M.).Y.Jiang gratefully acknowledges the Beijing Nova Program of Science and Technology(Z191100001119108).
文摘Selective and temporal control over protein activity is of great importance for the advancement of the protein of interest into precise molecular medicine.Simply installing synthetic ligands to proteins for activity regulation,however,is often obscured by either nonspecificity or insufficient efficiency.This study reports a chemical approach in which enzymatic cascade reactions were designed for selective activation of pro-protein both in vitro and in vivo.Specifically,the system consisted of aromatic boronic-acid-modified nanoparticles,reactive oxygen species(ROS)-responsive pro-protein(RNase A-NBC),a small molecule drug,β-Lapachone(β-Lap),and strategically screened synthetic lipids,required for the assembly of the nanocomplexes.Once target-delivered into tumor cells,the reduction ofβ-Lap produces massive H2O2 in response to NAD(P)H quinone oxidoreductase 1(NQO1),a tumor-specific enzyme,which triggers further induction by selective chemical modification of ROS-responsive cytosolic protein ribonuclease A(RNase A)-NBC,thus,switching from“inert”pro-protein to active therapeutics,that ultimately prohibit tumor cell growth.Moreover,the designed enzymatic cascade activation of the pro-protein was effective in vivo,displaying superior therapeutic efficacy to either the pro-protein alone or theβ-Lap via tumor-targeted delivery and the consequent suppression of the tumor growth.As both RNase A andβ-Lap have been evaluated clinically as antitumor therapeutics,our chemical multi-step cascade methodology is,therefore,a promising strategy for selective modulation of pro-protein chemistry in the living system for fundamental investigations,favorable toward potential anticancer applications.
文摘The cytochrome P411 enzyme is a variant of cytochrome P450_(BM3) from Bacillus megaterium whose active site is an iron porphyrin imine([Fe(Por)(NH)]^(-))specie.This specie has been reported to successfully promote the primary amination of benzylic and allylic C(sp^(3))-H bonds.We employed density functional theory to study the electronic structure of the active site of P411 enzyme and the primary amination of C-H bond reaction that it catalyzes.The calculated spin densities and orbital values indicate the existence of resonance in this specie;namely,[(por)(–OH)Fe^(Ⅳ)–N^(2-)–H]^(-)↔[(por)(–OH)Fe^(Ⅲ)–N^(·-)–H]^(-).The amination of C(sp^(3))-H bonds consists of two main reaction steps:hydrogen-atom abstraction and radical recombination,and the former is demonstrated to be the rate-determining step.Furthermore,we studied the regioselectivity of the amination of primary and secondary C(sp^(3))-H bonds.Our calculations indicated that the secondary C(sp^(3))-H bonds of the substrate would be more favored for the activation by P411 enzyme.These results provide valuable information for understanding the properties and selectivity of C-H/C-N bond-activation reactions catalyzed by the P411 enzyme or other similar enzymes.
