China
Africa
Explore chapters and articles related to this topic
Enzyme Catalysis
Published in Harvey W. Blanch, Douglas S. Clark, Biochemical Engineering, 1997
Harvey W. Blanch, Douglas S. Clark
Electrophilic catalysts, in contrast to nucleophilic catalysis, act by withdrawing electrons from the reaction center of the intermediate and are thus electron sinks. They stabilize a negative charge. Examples of this mechanism involve coenzymes thiamine pyrophosphate and pyridoxal phosphate. In many cases, including these coenzymes, electrophilic catalysis involves the formation of Schiff bases. For example, acetoacetate decarboxylase catalyzes the decarboxylation of acetoacetate to acetone and CO2. The mechanism involves the formation of a Schiff base involving a lysine residue.
Impact of exogenous nicotine on the morphological, physio-biochemical, and anatomical characteristics in Capsicum annuum
Published in International Journal of Phytoremediation, 2022
Rami Alkhatib, Batool Alkhatib, Nour Abdo
Nicotine is synthesized from the polyamine putrescine, directly from ornithine, catalyzed by ornithine decarboxylase, or indirectly from arginine catalyzed by arginine decarboxylase. Nicotine is synthesized in the roots and then transported to the shoot by the xylem (Selmar, Engelhardt, et al. 2015). Moreover, Jasmonic acid at the root zone plays a crucial role in regulating the gene expression as well as in stimulating synthesis of the enzymes required for nicotine biosynthesis (Shoji et al.2008; Zhang et al. 2012; Afrin et al. 2015). In addition to nicotine synthesis endogenously, there are generally three nicotine sources for contamination of plant, such as contaminations by smokers (smoke of cigarettes/nicotine residues at the fingers of harvesters) and nicotine which is taken up from the soil (e.g. resulting from butts of cigarettes thrown away).
Effects of pyruvate decarboxylase (pdc1, pdc5) gene knockout on the production of metabolites in two haploid Saccharomyces cerevisiae strains
Published in Preparative Biochemistry & Biotechnology, 2022
Wen Zhang, Jie Kang, Changli Wang, Wenxiang Ping, Jingping Ge
Ethanol is the main metabolite of S. cerevisiae, and pyruvate decarboxylase is the cytoplasmic enzyme at the fulcrum between fermentation and sugar catabolism.[20] Therefore, the Pyruvate decarboxylase 1 (pdc1) and Pyruvate decarboxylase 5 (pdc5) genes were knocked out by the Cre/loxP system to observe the changes in growth metabolism and the difference in growth metabolism between the MATa and MATα types of haploid S. cerevisiae. To obtain haploid strains with a high yield of 2,3-butanediol, the selection of strains for the industrial production of 2,3-butanediol was expanded. At the same time, this method lays a theoretical foundation for obtaining excellent haploid strain hybridization and provides valuable resources for breeding planning and quantitative genetic research.[21]
Optimization of fermented Perilla frutescens seeds for enhancement of gamma-aminobutyric acid and bioactive compounds by Lactobacillus casei TISTR 1500
Published in Preparative Biochemistry and Biotechnology, 2019
Arthitaya Kawee-ai, Phisit Seesuriyachan
As aforementioned above, the use of GABA-producing LAB strains as starter cultures in perilla seeds fermentation can help to achieve fermented perilla seed juice with GABA. LAB with glutamate decarboxylase could catalyze the α-decarboxylation of glutamate into GABA.[19] Perilla seeds contained glutamate more than 200 mg/g protein,[20] thus, the increase of GABA after fermentation might be due to glutamate consumption during LAB fermentation. LAB could increase GABA concentration of perilla seed pulp up to 120% (1.2 folds) at the peaks (Figure 1C). However, the decrease of GABA concentration after its peak might be due to the presence of organic and/or phenolic compounds, which resulted in an acidic environment that inhibits the growth of LAB strains.[11] From the results, L. casei TISTR 1500 was selected in the following experiments because of its rapid produced GABA.