In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPL...In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. (l)-2-amino-3-(carboxymethylthio)propionic acid was used as the internal standard (I.S.). After a protein precipitation extraction with acetonitrile, dencichine and the I.S. were chromatographed on an Xterra MS-C18 column. The mobile phase was consisted of 20mmol/L ammonium acetate solution-acetonitrile (35:65, V/V) at a flow rate of 0.2 mL/min. The detection was performed on a triple quadrupole mass via electrospray ionization (ESI) source in the positive mode. The intra- and inter-day precision (relative standard deviation, R.S.D.) values of dencichine were below 6.7%. The extraction recoveries were up 85%. The lower limit of quantification was 20 ng/ml, which was sensitive enough to detect the analyte. The HPLC-MS/MS method was successfully applied to the pharmacokinetic study after an intravenous administration of dencichine in Sprague-Dawley (SD) rat.展开更多
Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the infl...Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.展开更多
Objective:This study aimed to clone and characterize the oxiranedicarboxylate hydrolase(ORCH) from Labrys sp.WH-1.Methods:Purification by column chromatography,characterization of enzymatic properties,gene cloning by ...Objective:This study aimed to clone and characterize the oxiranedicarboxylate hydrolase(ORCH) from Labrys sp.WH-1.Methods:Purification by column chromatography,characterization of enzymatic properties,gene cloning by protein terminal sequencing and polymerase chain reaction(PCR),and sequence analysis by secondary structure prediction and multiple sequence alignment were performed.Results:The ORCH from Labrys sp.WH-1 was purified 26-fold with a yield of 12.7%.It is a monomer with an isoelectric point(pl) of 8.57 and molecular mass of 30.2 kDa.It was stable up to 55℃with temperature at which the activity of the enzyme decreased by 50% in 15 min(T5015) of 61℃and the half-life at 50℃(t1/2,50℃) of 51 min and was also stable from pH 4 to 10,with maximum activity at 55℃and pH 8.5.It is a metal-independent enzyme and strongly inhibited by Cu2+,Ag+,and anionic surfactants.Its kinetic parameters(Km,kcat,and kcat/Km) were 18.7 mmol/L,222.3 s-1,and 11.9 mmol/(L s),respectively.The ORCH gene,which contained an open reading frame(ORF) of 825 bp encoding 274 amino acid residues,was overexpressed in Escherichia coli and the enzyme activity was 33 times higher than that of the wild strain.Conclusions The catalytic efficiency and thermal stability of the ORCH from Labrys sp.WH-1 were the best among the reported ORCHs,and it provides an alternative catalyst for preparation of L(+)-2,3-dihydrobutanedioic acid.展开更多
文摘目的寻找能将氨基酸侧链的羟基、巯基与二元羧酸连接成酯的方法。方法分别以L 丝氨酸和L 半胱氨酸为起始物 ,采用叔丁氧羰基、苄酯或二苯甲酯形式保护 ,分别与丁二酸单苄酯、草酸单苄酯、丁二酸单叔丁酯缩合成酯 ,合成了 3个未见文献报道的化合物O (4 苄氧丁二酰基 ) N 叔丁氧羰基 L 丝氨酸苄酯 (4 )、O (2 苄氧草酰基 ) N 叔丁氧羰基 L 丝氨酸苄酯 (8)、S (4 叔丁氧丁二酰基 ) N 叔丁氧羰基 L 半胱氨酸二苯甲酯 (12 )。化合物 4经氢解合成未见文献报道的化合物O 丁二酰基 N 叔丁氧羰基 L 丝氨酸 (5 )。化合物 5经酸解得到O 丁二酰基 L 丝氨酸(6)。结果与结论目标化合物的结构经光谱确证。通过这种方法二元羧酸能与氨基酸的羟基。
文摘In order to quantitate dencichine in biological samples, a selective and sensitive method for the determination of dencichine in rat plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. (l)-2-amino-3-(carboxymethylthio)propionic acid was used as the internal standard (I.S.). After a protein precipitation extraction with acetonitrile, dencichine and the I.S. were chromatographed on an Xterra MS-C18 column. The mobile phase was consisted of 20mmol/L ammonium acetate solution-acetonitrile (35:65, V/V) at a flow rate of 0.2 mL/min. The detection was performed on a triple quadrupole mass via electrospray ionization (ESI) source in the positive mode. The intra- and inter-day precision (relative standard deviation, R.S.D.) values of dencichine were below 6.7%. The extraction recoveries were up 85%. The lower limit of quantification was 20 ng/ml, which was sensitive enough to detect the analyte. The HPLC-MS/MS method was successfully applied to the pharmacokinetic study after an intravenous administration of dencichine in Sprague-Dawley (SD) rat.
文摘Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ19C200001)the Education Department of Zhejiang Province Scientific Research Project(No.Y201737925)+1 种基金the Zhejiang Provincial Key Laboratory for Chemical and Biological Processing Technology of Farm Products(No.2016KF0048)the Key Laboratory of Bioorganic Synthesis of Zhejiang Province(No.20170110),China
文摘Objective:This study aimed to clone and characterize the oxiranedicarboxylate hydrolase(ORCH) from Labrys sp.WH-1.Methods:Purification by column chromatography,characterization of enzymatic properties,gene cloning by protein terminal sequencing and polymerase chain reaction(PCR),and sequence analysis by secondary structure prediction and multiple sequence alignment were performed.Results:The ORCH from Labrys sp.WH-1 was purified 26-fold with a yield of 12.7%.It is a monomer with an isoelectric point(pl) of 8.57 and molecular mass of 30.2 kDa.It was stable up to 55℃with temperature at which the activity of the enzyme decreased by 50% in 15 min(T5015) of 61℃and the half-life at 50℃(t1/2,50℃) of 51 min and was also stable from pH 4 to 10,with maximum activity at 55℃and pH 8.5.It is a metal-independent enzyme and strongly inhibited by Cu2+,Ag+,and anionic surfactants.Its kinetic parameters(Km,kcat,and kcat/Km) were 18.7 mmol/L,222.3 s-1,and 11.9 mmol/(L s),respectively.The ORCH gene,which contained an open reading frame(ORF) of 825 bp encoding 274 amino acid residues,was overexpressed in Escherichia coli and the enzyme activity was 33 times higher than that of the wild strain.Conclusions The catalytic efficiency and thermal stability of the ORCH from Labrys sp.WH-1 were the best among the reported ORCHs,and it provides an alternative catalyst for preparation of L(+)-2,3-dihydrobutanedioic acid.
