The chiral oxiranecarboxylic acids or esters 2a-e were obtained with lipase (CCL) in aqueous-organic system.The ee and the absolute configurations of the products were determined.
The life cycle analysis of biodiesel production from palm oil (PO) involves 3 stages: 1) Cultivation;2) Oil Extraction and 3) Transesterification of PO. There are several different approaches to the production process...The life cycle analysis of biodiesel production from palm oil (PO) involves 3 stages: 1) Cultivation;2) Oil Extraction and 3) Transesterification of PO. There are several different approaches to the production process. The enzyme catalyzed process, was investigated and its environmental performance was compared with the conventional alkali-catalyzed process by using life cycle analysis (LCA). The enzyme catalyzed process is found to be technically a simpler production process and offers the production of less environmentally damaging wastes.展开更多
The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distingushing inhibition type was given and the methods for calculat...The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distingushing inhibition type was given and the methods for calculating kinetic parameters, KM,Ki and Urn were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation of o-dihydroxybenzene by m-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type, KM=6.224×10-3 mol L-1, Ki=2. 363 × 10-2 mol. L-1.展开更多
The enzyme unit U,by its definition,is the amount of enzyme that catalyses the transformation of one micromole of substrate per minute under standard assay conditions.However,in practical use,it is identical with micr...The enzyme unit U,by its definition,is the amount of enzyme that catalyses the transformation of one micromole of substrate per minute under standard assay conditions.However,in practical use,it is identical with micromole or microgram per minute,which deviates from the essence of the definition as a measure of amount of substance.Such usage appears in many publications that involve enzyme kinetics and conveys obscure signification.In this article,we solved the confusion by regarding the unit U as a measure of amount of enzyme having a specified catalytic activity just like the basic SI unit mole(symbol mol) defined as the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of carbon 12.We introduced the concept of unit rate,ru,which is defined as the rate of a reaction mediated by 1 U enzyme,in calculating the enzyme units in an amount of enzyme so as to avoid the inconsistence of the expression with the definition of enzyme unit.The method can also be applied to the case of katal,the recommended SI unit of enzyme activity.展开更多
Enzyme catalyzed reaction of o phenylenediamine (OPD) H\-2O\-2 horseradish peroxidase (HRP) voltammetric enzyme linked immunoassay system has been studied in detail with electrochemical analysis, high performance liqu...Enzyme catalyzed reaction of o phenylenediamine (OPD) H\-2O\-2 horseradish peroxidase (HRP) voltammetric enzyme linked immunoassay system has been studied in detail with electrochemical analysis, high performance liquid chromatography (HPLC), ultraviolet/visible (UV/Vis) spectroscopy, infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The pure product of H\-2O\-2 oxidizing OPD catalyzed by HRP was prepared with chemical method. The experimental results of voltammetry and HPLC indicate that only one product of enzyme catalyzed reaction has been obtained under the selected enzyme catalyzed reaction conditions. Identifications by UV/Vis spectrum, IR spectrum and 13 C NMR spectrum show that the product is 2,3 diaminophenazine. The processes of the enzyme catalyzed reaction and the electroreduction of the product of the enzyme catalyzed reaction are described.展开更多
The resolutions of both enantiomers of the ornidazole and sec-nidazole were achieved with high enantiomeric excesses (ee > 99%) by acylation of the corresponding racemates with vinylac-etate in the presence of lipa...The resolutions of both enantiomers of the ornidazole and sec-nidazole were achieved with high enantiomeric excesses (ee > 99%) by acylation of the corresponding racemates with vinylac-etate in the presence of lipase Amano AK (from Pseudomonas sp.). The assignments of the absolute configurations of ( + ) or ( - )-ornidazole and secnidazole are described.展开更多
Optically active 1-aryl-2,3-allenols were obtained via CCL-mediated kinetic resolution of the racemic allenols. The substitution pattern of the aromatic ring, regarding to both the type of the substituent and its posi...Optically active 1-aryl-2,3-allenols were obtained via CCL-mediated kinetic resolution of the racemic allenols. The substitution pattern of the aromatic ring, regarding to both the type of the substituent and its position on the aromatic ring, was found to be critical for the kinetic resolution of 1-aryl-2,3-allenols.展开更多
Kinetic resolution of racemic 2-chloro-1-（3,4-dichlorophenyl）ethanol was performed by free Alcaligene sp. lipase-catalyzed irreversible transesterification affording the （R）-isomer with ≥95% ee and the （S）-isom...Kinetic resolution of racemic 2-chloro-1-（3,4-dichlorophenyl）ethanol was performed by free Alcaligene sp. lipase-catalyzed irreversible transesterification affording the （R）-isomer with ≥95% ee and the （S）-isomer with ≥90% ee. The activity of lipase Alcaligene sp. strongly depends on the basicity of the reaction system, and an organic base such as triethylamine can enhance the activity of the lipase and enantioselectivity markedly.展开更多
Novel polycarbonates from 5-allyloxy-1, 3-dioxan-2-one （ATMC） with 5, 5-dimethyl- 1, 3-dioxan-2-one （DTC） were successfully synthesized for the first time using immobilized porcine pancreas lipase （IPPL） as cata...Novel polycarbonates from 5-allyloxy-1, 3-dioxan-2-one （ATMC） with 5, 5-dimethyl- 1, 3-dioxan-2-one （DTC） were successfully synthesized for the first time using immobilized porcine pancreas lipase （IPPL） as catalyst. The resulting copolymers were characterized by IR, ^1H NMR, ^13C NMR and GPC. The molecular weight （Mn） of the copolymer with molar feed ratio of 10：90 （ATMC：DTC） was 9300 and the polydispersity was 1.31, while the Mn increased to 14300 and polydispersity of 1.25 with the feed ratio of 50：50. Moreover, the composition of the copolymers agreed well with the monomer feed.展开更多
文摘The chiral oxiranecarboxylic acids or esters 2a-e were obtained with lipase (CCL) in aqueous-organic system.The ee and the absolute configurations of the products were determined.
文摘The life cycle analysis of biodiesel production from palm oil (PO) involves 3 stages: 1) Cultivation;2) Oil Extraction and 3) Transesterification of PO. There are several different approaches to the production process. The enzyme catalyzed process, was investigated and its environmental performance was compared with the conventional alkali-catalyzed process by using life cycle analysis (LCA). The enzyme catalyzed process is found to be technically a simpler production process and offers the production of less environmentally damaging wastes.
文摘The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distingushing inhibition type was given and the methods for calculating kinetic parameters, KM,Ki and Urn were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation of o-dihydroxybenzene by m-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type, KM=6.224×10-3 mol L-1, Ki=2. 363 × 10-2 mol. L-1.
基金Funded by the Scientific Research Foundation for Returned Scholars of the Ministry of Education of China (No. (2010)609-1)the Key Project of the Ministry of Education of China (No. 10971)the Science and Technology Research Project of Chongqing Education Commission (No. KJ08A02)
文摘The enzyme unit U,by its definition,is the amount of enzyme that catalyses the transformation of one micromole of substrate per minute under standard assay conditions.However,in practical use,it is identical with micromole or microgram per minute,which deviates from the essence of the definition as a measure of amount of substance.Such usage appears in many publications that involve enzyme kinetics and conveys obscure signification.In this article,we solved the confusion by regarding the unit U as a measure of amount of enzyme having a specified catalytic activity just like the basic SI unit mole(symbol mol) defined as the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of carbon 12.We introduced the concept of unit rate,ru,which is defined as the rate of a reaction mediated by 1 U enzyme,in calculating the enzyme units in an amount of enzyme so as to avoid the inconsistence of the expression with the definition of enzyme unit.The method can also be applied to the case of katal,the recommended SI unit of enzyme activity.
文摘Enzyme catalyzed reaction of o phenylenediamine (OPD) H\-2O\-2 horseradish peroxidase (HRP) voltammetric enzyme linked immunoassay system has been studied in detail with electrochemical analysis, high performance liquid chromatography (HPLC), ultraviolet/visible (UV/Vis) spectroscopy, infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The pure product of H\-2O\-2 oxidizing OPD catalyzed by HRP was prepared with chemical method. The experimental results of voltammetry and HPLC indicate that only one product of enzyme catalyzed reaction has been obtained under the selected enzyme catalyzed reaction conditions. Identifications by UV/Vis spectrum, IR spectrum and 13 C NMR spectrum show that the product is 2,3 diaminophenazine. The processes of the enzyme catalyzed reaction and the electroreduction of the product of the enzyme catalyzed reaction are described.
基金Project supported by the National Natural Science Foundation of China(No.297912045)and the Major State Basic Research Development Program(No.G2000 077506).
文摘The resolutions of both enantiomers of the ornidazole and sec-nidazole were achieved with high enantiomeric excesses (ee > 99%) by acylation of the corresponding racemates with vinylac-etate in the presence of lipase Amano AK (from Pseudomonas sp.). The assignments of the absolute configurations of ( + ) or ( - )-ornidazole and secnidazole are described.
基金Project supported by the National Natural Sciences Foundation of China and the Major State Basic Research Development Program (No. G2000077500).
文摘Optically active 1-aryl-2,3-allenols were obtained via CCL-mediated kinetic resolution of the racemic allenols. The substitution pattern of the aromatic ring, regarding to both the type of the substituent and its position on the aromatic ring, was found to be critical for the kinetic resolution of 1-aryl-2,3-allenols.
基金Project supported by the Doctoral Foundation of Qingdao University of Science and Technology （No. 0022266）, the Program for New Century Excellent Talents in Universities （No. NCET-04-0649）, and the Natural Science Foundation of Shandong Province （No. Z2006B01）.
文摘Kinetic resolution of racemic 2-chloro-1-（3,4-dichlorophenyl）ethanol was performed by free Alcaligene sp. lipase-catalyzed irreversible transesterification affording the （R）-isomer with ≥95% ee and the （S）-isomer with ≥90% ee. The activity of lipase Alcaligene sp. strongly depends on the basicity of the reaction system, and an organic base such as triethylamine can enhance the activity of the lipase and enantioselectivity markedly.
基金The authors are grateful for the financial support of the National Natural Science Foundation of China （No. 20104005）.
文摘Novel polycarbonates from 5-allyloxy-1, 3-dioxan-2-one （ATMC） with 5, 5-dimethyl- 1, 3-dioxan-2-one （DTC） were successfully synthesized for the first time using immobilized porcine pancreas lipase （IPPL） as catalyst. The resulting copolymers were characterized by IR, ^1H NMR, ^13C NMR and GPC. The molecular weight （Mn） of the copolymer with molar feed ratio of 10：90 （ATMC：DTC） was 9300 and the polydispersity was 1.31, while the Mn increased to 14300 and polydispersity of 1.25 with the feed ratio of 50：50. Moreover, the composition of the copolymers agreed well with the monomer feed.
