Mammalian cells express two isoforms of Cu- and Zn-containing superoxide dismutases（SODs）, CuZn-SOD and extracellular SOD（EC-SOD）, involved in the defense system against reactive oxygen species（ROS）. The two SOD...Mammalian cells express two isoforms of Cu- and Zn-containing superoxide dismutases（SODs）, CuZn-SOD and extracellular SOD（EC-SOD）, involved in the defense system against reactive oxygen species（ROS）. The two SODs have structurally homologous centre domain with distinct N- and C-terminuses, resulting in the different characteristics of the structure and function of the two molecules. We generated a hybrid SOD molecule（namely hy- SOD） via replacing the N- and C-terminuses of hCuZnSOD with the counterparts of hEC-SOD. The hySOD was expressed in host Pichia pastoris and the purified protein was a dimer with a molecular weight of about 34000. A series of activity analyses indicates that the hySOD is similar to hEC-SOD in heat-stability, and has the activity of protecting the host cell against heat shock and oxidative stress. Our results show evidence for the study on the compound activity of multiple SOD molecules, and may be important for understanding the relationship between structure and function of hEC-SOD and hCuZnSOD.展开更多
The development of industrial biotechnology has created an increasing demand for alkaline lipolytic enzymes with functional diversity. In this study, an alkaline soil metagenomic library was constructed to search for ...The development of industrial biotechnology has created an increasing demand for alkaline lipolytic enzymes with functional diversity. In this study, an alkaline soil metagenomic library was constructed to search for new lipolytic enzymes. Two novel gene encoded alkaline esterases（designated as estA and estB） were isolated by functional screening from the library. The estA gene consisted of 834 bp and coded for 277 amino acids with a molecular mass of 29998. Amino acid sequence homology analysis indicates that EstA belongs to α/β hydrolase fold family 4.4（abH4.4）, with EstA being the smallest member of that family yet reported. The estB gene consisted of 1185 bp and encoded 394 amino acids with a theoretical molecular mass of 40090. Its conserved domain analysis shows that EstB belongs to the GDSL hydrolase superfamily. Both EstA and EstB exhibit only moderate identity（〈38%） in amino acid sequence to the known lipolytic enzyme genes in the database. The two genes were respectively expressed in Escherichia coli and the protein products were purified for functional characterization. While the expressed EstA did not exhibit the functional properties that were superior to those of other esterases previously reported, the EstB was stable at temperature up to 45 ℃ and its maximum activity was measured to be 53.6 U/mg at pH=10. Both the en- zymes have further enriched the diversity of the lipolytic enzymes database and also appear to be promising biocatalysts for potential biotechnological application.展开更多
To overcome ampicillin-resistance of bacteria which is believed to attribute their endogenous B-lactamase, we designed three 10-23 DNAzymes（Dz1, Dz2. Dz3） targeting the coding region of B-lactamase mRNA and examined...To overcome ampicillin-resistance of bacteria which is believed to attribute their endogenous B-lactamase, we designed three 10-23 DNAzymes（Dz1, Dz2. Dz3） targeting the coding region of B-lactamase mRNA and examined their inhibitory capabilities of the ampicillin-resistance of TEM-1 and TEM-3 bacteria. Dz1 was a traditional 10-23 DNAzyme, Dz2 was the mutant of Dz1 by addition of the protected nucleotide to each ann of the enzyme, and Dz3 was a mutant of Dz1 at antisense arms of which phosphorothioate modifications were made. Kinetic analysis, bacterial growth, and β-lactamase activity measurement showed that all the three DNAzymes worked efficiently in vitro and in vivo. A 9 hours bacterial growth inhibition test showed that the inhibition rates of TEM-1 bacteria by Dz1, Dz2, and Dz3 were 27%, 50%, and 29%, respectively. In addition, the inhibition rates of TEM-3 bacteria by those three DNAzymes were found io be 49%, 58%, and 45%, respectively. The current findings suggest that DNAzymes may become potential candidates of alternative inhibitors for bacteria drug-resistance.展开更多
Peroxiredoxins（Prxs） are a large family of antioxidant enzymes of various types that take part in signal transduction via decomposing reactive oxygen species（ROS）. Although extensive efforts have been made over th...Peroxiredoxins（Prxs） are a large family of antioxidant enzymes of various types that take part in signal transduction via decomposing reactive oxygen species（ROS）. Although extensive efforts have been made over the last decades in understanding the structures and functions of Prxs, type II Prxs in monocots are hardly studied. In this work, a monocot type II Prx gene homologue from Chinese wildrye（Leymus Chinensis）, designated as LcTpxII, was isolated and characterized. LcTpxII encoding a 162-amino acid protein contains a thioredoxin domain and a cysteine residue at position 51, suggesting that it is a member of the Prxs family. The LcTpxII is capable of decomposing H2O2 and protecting plasmid DNA from damage caused by ROS. The expression of LcTpxII in Chinese wildrye was induced by 400 mmol/L NaCl and 100 mmol/L Na2CO3 in the experiment. The overexpression of LcTpxII enhances the tolerance of transgenic yeast to 1.6 mol/L NaCl and 10 mmol/L Na2CO3.展开更多
The molecular mechanism of triple-negative breast cancer（TNBC） remains unclear, and there has been no effective targeted therapy for it. A better understanding of the mechanisms of TNBC is urgently needed to identif...The molecular mechanism of triple-negative breast cancer（TNBC） remains unclear, and there has been no effective targeted therapy for it. A better understanding of the mechanisms of TNBC is urgently needed to identify new therapeutic targets. In this study, eight cases of premenopausal TNBC patients were collected, and a comparative proteomic analysis of their breast cancer tissues and matched paraneoplastic ones was performed via isobaric tags for relative and absolute quantitation（iTRAQ） technology coupled with two-dimensional liquid chromatography-tandem mass spectrumetry（2D LC-MS/MS）. The researches result in the identification of 1254 nonredundant proteins, of which 1243 proteins reached the strict quantitative standard. The quantitative comparison reveal that among the 214 proteins, 81 proteins significantly increased and 133 proteins decreased in TNBC tissues compared to corresponding ones in control. The Gene Ontology（GO） annotations and pathway analysis show their distributions in GO and the marked functions, as well as the closely related signal transduction pathways involved in extra cellular matrix （ECM）-receptor interaction, protein digestion and absorption, renin-angiotensin system, complement and coagulation cascades and focal adhesion. This pilot study will lay a foundation for further searching for therapeutic targets of TNBC and exploring the molecular mechanism, which can also be extended as a part of a large scale biomarker discovery plan.展开更多
文摘Mammalian cells express two isoforms of Cu- and Zn-containing superoxide dismutases（SODs）, CuZn-SOD and extracellular SOD（EC-SOD）, involved in the defense system against reactive oxygen species（ROS）. The two SODs have structurally homologous centre domain with distinct N- and C-terminuses, resulting in the different characteristics of the structure and function of the two molecules. We generated a hybrid SOD molecule（namely hy- SOD） via replacing the N- and C-terminuses of hCuZnSOD with the counterparts of hEC-SOD. The hySOD was expressed in host Pichia pastoris and the purified protein was a dimer with a molecular weight of about 34000. A series of activity analyses indicates that the hySOD is similar to hEC-SOD in heat-stability, and has the activity of protecting the host cell against heat shock and oxidative stress. Our results show evidence for the study on the compound activity of multiple SOD molecules, and may be important for understanding the relationship between structure and function of hEC-SOD and hCuZnSOD.
基金Supported by the National High-tech Research and Development Program of China(No.2007AA021307)
文摘The development of industrial biotechnology has created an increasing demand for alkaline lipolytic enzymes with functional diversity. In this study, an alkaline soil metagenomic library was constructed to search for new lipolytic enzymes. Two novel gene encoded alkaline esterases（designated as estA and estB） were isolated by functional screening from the library. The estA gene consisted of 834 bp and coded for 277 amino acids with a molecular mass of 29998. Amino acid sequence homology analysis indicates that EstA belongs to α/β hydrolase fold family 4.4（abH4.4）, with EstA being the smallest member of that family yet reported. The estB gene consisted of 1185 bp and encoded 394 amino acids with a theoretical molecular mass of 40090. Its conserved domain analysis shows that EstB belongs to the GDSL hydrolase superfamily. Both EstA and EstB exhibit only moderate identity（〈38%） in amino acid sequence to the known lipolytic enzyme genes in the database. The two genes were respectively expressed in Escherichia coli and the protein products were purified for functional characterization. While the expressed EstA did not exhibit the functional properties that were superior to those of other esterases previously reported, the EstB was stable at temperature up to 45 ℃ and its maximum activity was measured to be 53.6 U/mg at pH=10. Both the en- zymes have further enriched the diversity of the lipolytic enzymes database and also appear to be promising biocatalysts for potential biotechnological application.
基金the National Natural Science Foundation of China(Nos.20771030 and 20671025)
文摘To overcome ampicillin-resistance of bacteria which is believed to attribute their endogenous B-lactamase, we designed three 10-23 DNAzymes（Dz1, Dz2. Dz3） targeting the coding region of B-lactamase mRNA and examined their inhibitory capabilities of the ampicillin-resistance of TEM-1 and TEM-3 bacteria. Dz1 was a traditional 10-23 DNAzyme, Dz2 was the mutant of Dz1 by addition of the protected nucleotide to each ann of the enzyme, and Dz3 was a mutant of Dz1 at antisense arms of which phosphorothioate modifications were made. Kinetic analysis, bacterial growth, and β-lactamase activity measurement showed that all the three DNAzymes worked efficiently in vitro and in vivo. A 9 hours bacterial growth inhibition test showed that the inhibition rates of TEM-1 bacteria by Dz1, Dz2, and Dz3 were 27%, 50%, and 29%, respectively. In addition, the inhibition rates of TEM-3 bacteria by those three DNAzymes were found io be 49%, 58%, and 45%, respectively. The current findings suggest that DNAzymes may become potential candidates of alternative inhibitors for bacteria drug-resistance.
基金Supported by the Transgenic Plant Research Special Program of China(No.2008ZX08003-005)the Technology Development Project of Jilin Province,China(Nos.20086029,20076016)
文摘Peroxiredoxins（Prxs） are a large family of antioxidant enzymes of various types that take part in signal transduction via decomposing reactive oxygen species（ROS）. Although extensive efforts have been made over the last decades in understanding the structures and functions of Prxs, type II Prxs in monocots are hardly studied. In this work, a monocot type II Prx gene homologue from Chinese wildrye（Leymus Chinensis）, designated as LcTpxII, was isolated and characterized. LcTpxII encoding a 162-amino acid protein contains a thioredoxin domain and a cysteine residue at position 51, suggesting that it is a member of the Prxs family. The LcTpxII is capable of decomposing H2O2 and protecting plasmid DNA from damage caused by ROS. The expression of LcTpxII in Chinese wildrye was induced by 400 mmol/L NaCl and 100 mmol/L Na2CO3 in the experiment. The overexpression of LcTpxII enhances the tolerance of transgenic yeast to 1.6 mol/L NaCl and 10 mmol/L Na2CO3.
基金Supported by the National Natural Science Foundation of China（No.81041098）.
文摘The molecular mechanism of triple-negative breast cancer（TNBC） remains unclear, and there has been no effective targeted therapy for it. A better understanding of the mechanisms of TNBC is urgently needed to identify new therapeutic targets. In this study, eight cases of premenopausal TNBC patients were collected, and a comparative proteomic analysis of their breast cancer tissues and matched paraneoplastic ones was performed via isobaric tags for relative and absolute quantitation（iTRAQ） technology coupled with two-dimensional liquid chromatography-tandem mass spectrumetry（2D LC-MS/MS）. The researches result in the identification of 1254 nonredundant proteins, of which 1243 proteins reached the strict quantitative standard. The quantitative comparison reveal that among the 214 proteins, 81 proteins significantly increased and 133 proteins decreased in TNBC tissues compared to corresponding ones in control. The Gene Ontology（GO） annotations and pathway analysis show their distributions in GO and the marked functions, as well as the closely related signal transduction pathways involved in extra cellular matrix （ECM）-receptor interaction, protein digestion and absorption, renin-angiotensin system, complement and coagulation cascades and focal adhesion. This pilot study will lay a foundation for further searching for therapeutic targets of TNBC and exploring the molecular mechanism, which can also be extended as a part of a large scale biomarker discovery plan.
