China
Africa
Explore chapters and articles related to this topic
Bioactive Metabolites
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Ayse Kose, Claire Remacle, Young-Woo Kim, Suphi S. Oncel, Murat Elibol
Both growth rates and lipid content should be improved on order to reduce the cost of lipid production in microalgae (Davis et al. 2011). To improve growth rates, efforts have been made to improve photosynthetic efficiency. Molecular targets showing improved growth rates include the sedoheptulose-1,7-bisphosphatase (SBPase) of the Calvin cycle and the phosphoenolpyruvate carboxylase. The SBPase of C. reinhardtii was expressed in a glycerol-producing halotolerant, Dunaliella bardawil. The D. bardawill transformant showed improved photosynthetic performance with increased total organic carbon content and osmoticum glycerol production (Fang et al. 2012). The downregulation of the C. reinhardtii phosphoenolpyruvate carboxylase (PEPCase), which catalyzes the transformation of phosphoenolpyruvate (PEP) into oxaloacetate while fixing CO2, led to a 20% increase in triacylglycerol (TAG) content and overall lower growth rates. On the contrary, overexpression of the enzyme led to increased growth rates (Deng et al 2014).
The Mannitol Enzyme II of the Bacterial Phosphotransferase System: A Functionally Chimaeric Protein with Receptor, Transport, Kinase, and Regulatory Activities
Published in James F. Kane, Multifunctional Proteins: Catalytic/Structural and Regulatory, 2019
Milton H. Saier, John E. Leonard
Several years ago Englesberg described a procedure for the isolation of glucose-methyl α-glucoside permease negative mutants in Salmonella typhimurium.40,41 Parental mutant strains which lack the enzyme, phosphoenolpyruvate carboxylase, due to a mutation in the ppc gene, cannot synthesize Krebs cycle intermediates from sugars which are metabolized via glycolysis. While ppc mutants can ordinarily grow if an exogenous source of citrate is available, the mutants cannot grow in minimal salts medium supplemented with citrate and glucose.40,41 The reason for glucose induced growth stasis is that glucose supresses synthesis of the citrate permease, thereby preventing uptake of citrate into the cells. On such media, mutants capable of growth arise which lack the glucose permease, and these mutants are defective for the glucose Enzyme II of the PTS.8 Moreover, glucose could be replaced by fructose or mannitol, as these sugars also repressed the synthesis of the citrate permease.8 Mutants isolated for their ability to grow on citrate plus fructose or citrate plus mannitol were frequently defective for the fructose or mannitol Enzyme II, respectively, as expected.
Nodulin Function and Nodulin Gene Regulation in Root Nodule Development
Published in Peter M. Gresshoff, Molecular Biology of Symbiotic Nitrogen Fixation, 2018
The soybean (G. max) nodulin Ngm-100 has been shown to be the subunit of sucrose synthase.119 Nodule-specific forms of enzymes that differ in physical, kinetic, or immunochemical properties from the corresponding enzymes in roots have been found for phosphoenolpyruvate carboxylase,120 choline kinase,121 xanthine dehydrogenase,122 purine nucleosidase,123 and malate dehydrogenase.124 They may prove to be the result of the expression of nodule-specific genes, but at the moment it is too early to conclude whether these nodule-specific forms are true nodulins or the result of nodule-specific modifications of root enzymes, derived from constitutively expressed genes.
An extensive review of experimental ochratoxicosis in poultry: II. Hemato-biochemical and immunological alterations along with other health issues
Published in Toxin Reviews, 2021
OTA is considered to be an important nephrotoxin as it seriously affects the functional stability of kidneys. Chronic exposure of OTA to birds leads to reduction in urine quantity, phenol clearance along with impaired glomerular as well as proximal tubular infiltration (Huff et al.1975). OTA causes structural changes in epithelial linings of renal tubules and these effects are most severe in the proximal convoluted tubules (Glahn 1993). Phosphoenolpyruvate carboxylase, an important enzyme of lipid peroxidation, is being inhibited through the adverse effects of OTA upon proximal tubules of kidneys. Along with this it also affects the functional ability of kidney to metabolize calcium (Betina 1989). It also causes lipid peroxidation in kidney microsomes leading to production of malondialdehyde ultimately causing lipid peroxidation in birds (Rahimtula et al.1988).
Effects of green tea supplementation on serum concentrations of adiponectin in patients with type 2 diabetes mellitus: a systematic review and meta-analysis
Published in Archives of Physiology and Biochemistry, 2023
Omid Asbaghi, Faezeh Fouladvand, Damoon Ashtary-Larky, Reza Bagheri, Razieh Choghakhori, Alexei Wong, Julien S. Baker, Amir Abbasnezhad
Adiponectin is the most abundant peptide secreted by adipocytes (Silva et al.2014) and is the key component in the interrelationship between adiposity, insulin resistance, and inflammation (Silva et al.2014). Prospective and longitudinal studies have reported that lower adiponectin concentrations are linked to a higher incidence of diabetes in different populations (Yatagai et al.2003). Therefore, adiponectin has attracted much attention because of its antidiabetic and anti-atherogenic effects and is considered to be a novel therapeutic tool for T2DM (Fang and Judd 2018). Adiponectin enhances insulin sensitivity through several mechanisms such as increasing intracellular translocation of glucose transporter type 4 (GLUT4) to the plasma membrane in muscles, which are mediated by adiponectin receptors (AdipoR1 and AdipoR2) (Fisman and Tenenbaum 2014; Achari and Jain 2017). In addition, adiponectin hampers gluconeogenesis by inhibiting the hepatic enzyme phosphoenolpyruvate carboxylase (Silva et al.2014). Furthermore, adiponectin inhibits the synthesis of fatty acids and stimulates their oxidation (Kadowaki et al.2006). Independently, adiponectin acts as an agonist of the peroxisome-proliferator activated receptor gamma (PPARG), thereby leading to additional uptake of plasmatic glucose (Kadowaki et al.2006). Finally, adiponectin enhances insulin sensitivity by increasing hepatic insulin receptor substrate 2 (IRS-2) expression via the macrophage-derived Interleukin-6 (IL-6)-dependent pathway (Awazawa et al.2011). Therefore, considering adiponectin’s biochemical functions, it can be assumed that adiponectin plays an important role in preventing the development of insulin resistance.
Use of an immobilised thermostable α-CA (SspCA) for enhancing the metabolic efficiency of the freshwater green microalga Chlorella sorokiniana
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Giovanna Salbitani, Sonia Del Prete, Francesco Bolinesi, Olga Mangoni, Viviana De Luca, Vincenzo Carginale, William A. Donald, Claudiu T. Supuran, Simona Carfagna, Clemente Capasso
Photosynthesis employs sunlight and the reaction between CO2 and H2O to generate carbohydrates and oxygen as a side product. This gas is necessary for the aerobic respiration but also promotes the formation of the ozone layer in the upper atmosphere. During the photosynthetic reactions, the energy of sunlight is converted into chemical energy, i.e., ATP and NADPH, which are thereafter involved in the biosynthesis of carbohydrates from CO2 as a unique carbon source1,2. The aerobic respiration (glucose + O2 → H2O + CO2), on the contrary, is the process of energy production, which converts sugars into carbon dioxide and water. These two opposite reactions influence the global carbon cycle, being fundamental for most life forms on earth2. The light-dependent reactions to form glucose and other carbohydrates are known as the Calvin-Benson cycle. There are three photosynthetic pathways, C3, C4, and CAM (Crassulacean Acid Metabolism) that exist among terrestrial plants3,4. In the C3 photosynthesis, which is the most ancestral form, the enzyme ribulose bisphosphate carboxylase-oxygenase (RuBisCO)5, which is present in the chloroplast stroma of C3 plants, combines the ribulose-1,5-bisphosphate (RuBP), a molecule containing five carbon atoms, with CO2 to form two molecules of phosphoglycerate (PGA, a 3-carbon molecule)6,7. In the C4 pathway, the CO2 is converted into bicarbonate, which is subsequently reacted with phosphoenolpyruvic acid (PEP), a 3-carbon molecule, in the presence of phosphoenolpyruvate carboxylase (PEPC)8. The product of this reaction is a 4-carbon molecule, oxaloacetic acid (OAA), which is thereafter reduced to malate, another four-carbon acid8. The CAM pathway was documented for the first time in plant families that are adapted to very arid regions, such as many epiphytes and succulents9. These plants have a dual pathway of carboxylation temporally separated into the same tissue. In the night with the stomata opening, the CO2 is fixed as an organic acid form of the anion malate by PEPC. In contrast, during the day, with the stomatal closure, the malic acid undergoes decarboxylation, determining an increase of CO2 around the enzyme RuBisCO of about 60 times the ambient levels, allowing the photosynthetic reaction typical of the C3 cycle mentioned above9. The RuBisCO enzyme also uses O2 as substrate, not only CO210. The rate of the oxygenation and carboxylation by RuBisCO is controlled by the levels of O2 and CO2 and is the primary factor in determining the efficiency of the photosynthetic process11. CAM is one example of a carbon-concentrating mechanism (CCM) in higher order plants, in which, as mentioned above, decarboxylation of malic acids affords supplementary amounts of CO2.