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Future Strategies for Commercial Biocatalysis
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Robert E. Speight, Karen T. Robins
Enzyme immobilisation and fusion protein generation strategies were both adopted in a one-pot four-enzyme system for the synthesis of dihydroxyacetone phosphate from glycerol (Fig. 1.2; Hartley et al., 2017). This work achieved in situ regeneration of ATP using acetate or pyruvate kinase for repeated phosphorylation of glycerol using glycerol kinase. The cofactor recycling was enhanced through novel fusion protein strategies that tethered the cofactor to the enzymes resulting in increased efficiencies (Scott et al., 2015). This one-pot system was coupled to an aldolase for the production of various chiral sugars. The one-pot enzyme cascade from glycerol to dihydroxyacetone phosphate including in situ ATP regeneration. The generation of dihydroxyacetone phosphate from glycerol-3-phosphate can be catalysed either by glycerol phosphate oxidase or by glycerol-3-phosphate dehydrogenase along with NAD+ reduction. The most efficient system avoided the need for additional cofactor recycling by following the glycerol phosphate oxidase path and included catalase to covert the potentially enzyme destabilising hydrogen peroxide back to oxygen and water. Reactions are not all balanced in the figure for simplicity.Adapted from Hartley et al. (2017).
Modulation of Lipid Biosynthesis by Stress in Diatoms
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Bing Huang, Virginie Mimouni, Annick Morant-Manceau, Justine Marchand, Lionel Ulmann, Benoit Schoefs
Glycerol is an important raw material for TAG synthesis. Glycerol-3-phosphate dehydrogenase (GPDH) is part of an important pathway in which the reduction of dihydroxyacetone phosphate (DHAP) from the glycolytic pathway is catalyzed into glycerol-3-phosphate (G3P) in a reversible manner. G3P is an essential precursor for DAG and TAG biosynthesis by the Kennedy pathway and may act as a bridge for carbon transfer between carbohydrate and lipid metabolism (Zulu et al., 2018). When glycerolipid synthesis is highly induced (nitrogen- or/and phosphorus-starvation), the utilization of G3P by the Kennedy pathway for TAG production might even be predominant on glycerol production. GPDH activity may therefore be important for lipid biosynthesis (Driver et al., 2017). In P. tricornutum, overexpressing the gene encoding the GPDH resulted in a 6.8-fold increase of the glycerol concentration per transformant cell compared with the WT. There was also a 60% increase in neutral lipid content despite a 20% decrease in cell concentration. FA profiling was also modified with the significant increase in the levels of C16- and C18-MUFA (Yao et al., 2014).
Increasing the Sensitivity of Adipocytes and Skeletal Muscle Cells to Insulin
Published in Christophe Wiart, Medicinal Plants in Asia for Metabolic Syndrome, 2017
Catecholamines released during stress, glucagon during fast and serotonin, are brought by the plasma to the surface of adipocytes where they bind to membrane receptor, activating adenylate cyclase increasing levels of cyclic adenosine monophosphate.351 This secondary messenger activates protein kinase A which in turn on both hormone sensitive lipase and perilipin-1.351 The phosphorylation of perilipin-1 induces the on adipocyte triglyceride lipase to convert triglycerides into diacylglycerol whereas hormone sensitive lipase catalyze the hydrolysis of diacylglycerol to monoacylglycerol. Monoacyl glycerol is hydrolyzed into glycerol and unesterified fatty acid by monoacylglycerol lipase.352 Unesterified fatty acids are transported to the cytoplasmic membrane by adipocyte fatty acid-binding protein.352 Hormone-sensitive lipase is inhibited by insulin and, in obese patients with insulin resistance the activation of hormone-sensitive lipase evokes an increase of secretion of nonesterified free fatty acids promoting the synthesis of very low-density lipoprotein by the liver, β-cells dysfunction and worsening of insulin resistance.353 Natural products with the ability to stimulate adipocyte hormone-sensitive lipase may conceptually be of usefulness to boost hydrolysis of stored triglycerides in adipocytes and to reduce adipose mass. One such compound is 5,6-dehydrokawain (Figure 4.25) from Alpinia zerumbet B.L. Burtt & R.M. Sm.354 which at 250 μg/mL reduced triglyceride contents in 3T3-L1 adipocytes by 63.4%, increased cytoplasmic cyclic adenosine monophosphate by 56.9%, inhibited glycerol-3-phosphate dehydrogenase by 90.5%, and induced glycerol release by 225% with concurrent increased of cytoplasmic cyclic adenosine monophosphate.355 This pyrone reduced triglyceride accumulation by 63.4%.355In vitro, 5,6-dehydrokawain inhibited porcine pancreatic lipase activity with an IC50 of 74.4 μg/mL (quercetin: 38.5 μg/mL).355 Terpinen-4-ol isolated from ginger given intravenously evoked an immediate and dose-dependent reduction of mean aortic blood pressure in deoxycorticosterone acetate-salt hypertensive Wistar rats by about 30% at 5 mg/kg.356
Hypolipidemic and anti-inflammatory properties of phenolic rich Butia odorata fruit extract: potential involvement of paraoxonase activity
Published in Biomarkers, 2020
Vanessa Plasse Ramos, Pamela Gonçalves da Silva, Pathise Souto Oliveira, Natália Pontes Bona, Mayara Sandrielly Pereira Soares, Juliane de Souza Cardoso, Jessica Fernanda Hoffmann, Fábio Clasen Chaves, Augusto Schneider, Roselia Maria Spanevello, Claiton Leoneti Lencina, Francieli Moro Stefanello, Rejane Giacomelli Tavares
Other present compounds, such as chlorogenic acid, has been investigated for its positive effect on glucose regulation, strong antioxidant, anti-inflammatory, and anticancer activities (Kong et al. 2018). Rutin is related to prevents hyperlipidaemia induced by high CHOL diet and promotes the excretion of faecal sterols, decreases the absorption of dietary cholesterol and lowers the plasma and hepatic cholesterol concentration (Monika and Geetha 2015). This compound can also reduce blood insulin, as well as inhibit glycerol-3-phosphate dehydrogenase, an enzyme linked to glycerol and triacylglycerol conversion in adipose tissue and liver (Hossain et al. 2016). In previous studies of our group, Oliveira et al. (2017) demonstrated that the extract of Eugenia uniflora, rich in phenolic compounds, prevented the increase of TG, glucose, CHOL, and LDL-C after a metabolic syndrome induced with a highly palatable diet lasting 150 days. Additionally, Cardoso et al. (2018) showed that the extract of E. uniflora and P. cattleianum prevented the increase in glucose and TG levels in an animal model of insulin resistance induced by dexamethasone.
Repurposing of rabeprazole as an anti-Trypanosoma cruzi drug that targets cellular triosephosphate isomerase
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Itzhel García-Torres, Ignacio De la Mora-De la Mora, Gabriel López-Velázquez, Nallely Cabrera, Luis Antonio Flores-López, Ingeborg Becker, Juliana Herrera-López, Roberto Hernández, Ruy Pérez-Montfort, Sergio Enríquez-Flores
The enzymatic activities of cellular TIM from epimastigotes and recombinant TcTIMs were assayed as described by Gómez-Puyou et al.42 as follows. The conversion of glyceraldehyde 3-phosphate (GAP) to dihydroxyacetone phosphate (DHAP) was monitored spectrophotometrically by the oxidation of the cofactor NADH at 340 nm using glycerol-3-phosphate dehydrogenase (α-GDH) as the coupling enzyme. For enzymatic assays, was used a reaction mixture that consisted of 1 mM GAP, 0.2 mM NADH, and 0.9 units/mL of α-GDH in TE buffer. The assays were initiated by adding to the reaction mixture, an aliquot (60 μg/mL) of total protein extracted from epimastigote cultures treated with Rbz or 5 ng/mL of recombinant TcTIM under a constant temperature of 25 °C.
Research on the hepatotoxicity mechanism of citrate-modified silver nanoparticles based on metabolomics and proteomics
Published in Nanotoxicology, 2018
Jiabin Xie, Wenying Dong, Rui Liu, Yuming Wang, Yubo Li
Choline is a constituent of lecithin and the precursor of acetylcholine, and two choline metabolic pathways may exist. On the one hand, choline can phosphorylate phosphorylcholine and participate in the biosynthesis of phosphatidylcholine. On the other hand, choline can be converted to glycine by dimethylglycine dehydrogenase and sarcosine dehydrogenase. Furthermore, phosphatidate phosphohydrolase can reportedly promote the synthesis of phosphatidylcholine, phosphatidylethanolamine and triacylglycerol (Simpson et al. 1989). Glycerol-3-phosphate is a key metabolite in the translocation of reducing power through mitochondrial glycerol-3-phosphate dehydrogenase. At the same time, glycerol-3-phosphate dehydrogenase, as a major link between carbohydrate metabolism and lipid metabolism, catalyzes the formation of ethanolamine lysophospholipids (Taleux et al. 2009). Glycerol phospholipids are highly biologically active molecules that are involved in inflammatory responses. When the liver is damaged, the expression of cytokine receptors in immune cells, including monocytes, macrophages and dendritic cells is inhibited. With increasing degrees of liver damage, the amounts of cytokines decreases, resulting in decreased liver synthesis, metabolism, and transformation functions. This study showed that the levels of tyrosine, tryptophan, and glycerophospholipid metabolites were reduced and tyrosine aminotransferase, and glycerol-3-phosphate dehydrogenase also showed a downward trend. These affects blocked the biosynthesis of phenylalanine, tyrosine and tryptophan and gave rise to abnormal glycerol phospholipid metabolism, which led to inflammatory reactions and liver damage.