A computational study on the mechanism for the decarboxylation of pyruvic acid to acetaldehyde catalyzed by pyruvate decarboxylase at the B3LYP/6-31G (d, p) level of theory is presented. The model employed is self-con...A computational study on the mechanism for the decarboxylation of pyruvic acid to acetaldehyde catalyzed by pyruvate decarboxylase at the B3LYP/6-31G (d, p) level of theory is presented. The model employed is self-contained and it does not resort to external groups to provide protons to the various structures in the mechanism. The potential energy surface points at the intramolecular proton transfer from the amino group of the pyrimidine ring in the enamine intermediate to the enol exocyclic carbon as the rate-determining step (with a barrier of 20.55 kcal·mol–1). This value is in reasonable agreement with an estimated barrier of 24.76 kcal·mol–1, derived from the experimental rate constant (4.0 10–5 s–1) for the decarboxylation of α-lactylthiamin.展开更多
Pyruvate, a final metabolite of glycogen, is widely distributed over many kinds of tissue fluids of human bodys. The determination for its contents is of clinical importance in gynaecology. Titrimetry, colorimetry and...Pyruvate, a final metabolite of glycogen, is widely distributed over many kinds of tissue fluids of human bodys. The determination for its contents is of clinical importance in gynaecology. Titrimetry, colorimetry and chromatography are common used methods. In recent years, enzymatic mthod has proved to be one of the most important determination techniques for its simplicity and fastness. However, in some cases, the use of purified enzymes as biocatalysts yields systems with a short useful lifetime owing, to enzyme instability A tiss展开更多
以运动发酵单胞菌的总DNA为模板,PCR扩增Zym om onas m obilis中的乙醇脱氢酶基因(adhB)和丙酮酸脱羧酶基因(p d c)。首先进行单个基因表达,基因表达产物经SDS-PAGE电泳分析和乙醛指示平板检测,确认有酶活性后,将这2个基因串联构建多顺...以运动发酵单胞菌的总DNA为模板,PCR扩增Zym om onas m obilis中的乙醇脱氢酶基因(adhB)和丙酮酸脱羧酶基因(p d c)。首先进行单个基因表达,基因表达产物经SDS-PAGE电泳分析和乙醛指示平板检测,确认有酶活性后,将这2个基因串联构建多顺反子表达质粒pSE-p d c-adhB,转入大肠杆菌DH 5α内,得重组工程菌株。工程菌株经IPTG诱导,分别在含10%葡萄糖和10%木糖培养基中于37℃培养72 h,有乙醇产生,酒精产率分别为对照菌株21倍和5倍。展开更多
文摘A computational study on the mechanism for the decarboxylation of pyruvic acid to acetaldehyde catalyzed by pyruvate decarboxylase at the B3LYP/6-31G (d, p) level of theory is presented. The model employed is self-contained and it does not resort to external groups to provide protons to the various structures in the mechanism. The potential energy surface points at the intramolecular proton transfer from the amino group of the pyrimidine ring in the enamine intermediate to the enol exocyclic carbon as the rate-determining step (with a barrier of 20.55 kcal·mol–1). This value is in reasonable agreement with an estimated barrier of 24.76 kcal·mol–1, derived from the experimental rate constant (4.0 10–5 s–1) for the decarboxylation of α-lactylthiamin.
基金Supported by the National Natural Science Foundation of China
文摘Pyruvate, a final metabolite of glycogen, is widely distributed over many kinds of tissue fluids of human bodys. The determination for its contents is of clinical importance in gynaecology. Titrimetry, colorimetry and chromatography are common used methods. In recent years, enzymatic mthod has proved to be one of the most important determination techniques for its simplicity and fastness. However, in some cases, the use of purified enzymes as biocatalysts yields systems with a short useful lifetime owing, to enzyme instability A tiss
文摘以运动发酵单胞菌的总DNA为模板,PCR扩增Zym om onas m obilis中的乙醇脱氢酶基因(adhB)和丙酮酸脱羧酶基因(p d c)。首先进行单个基因表达,基因表达产物经SDS-PAGE电泳分析和乙醛指示平板检测,确认有酶活性后,将这2个基因串联构建多顺反子表达质粒pSE-p d c-adhB,转入大肠杆菌DH 5α内,得重组工程菌株。工程菌株经IPTG诱导,分别在含10%葡萄糖和10%木糖培养基中于37℃培养72 h,有乙醇产生,酒精产率分别为对照菌株21倍和5倍。
