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Burkholderia Species
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Natalia Alvarez-Santullano, Pamela Villegas, Mario Sepúlveda, Ariel Vilchez, Raúl Donoso, Danilo Perez-Pantoja, Rodrigo Navia, Francisca Acevedo, Michael Seeger
In Paraburkholderia and Burkholderia strains, sucrose is hydrolyzed by sucrose hydrolase into glucose and fructose. Glucose catabolism is carried out through enzymes of the glycolysis, pentose phosphate, and ED pathways (Figure 5.4). Glucose is phosphorylated by glucokinase into glucose-6-phosphate, which undergoes oxidation by glucose-6-phosphate dehydrogenase with NADPH production and subsequent hydrolysis by 6-phosphogluconolactonase to yield gluconate-6-phosphate, which can be further degraded by the ED pathway or pentose phosphate pathway. Fructose is phosphorylated by fructokinase into fructose-6-phosphate, which may be isomerized into glucose-6-phosphate and channeled into gluconate-6-phosphate, entering the ED pathway or the pentose phosphate pathway. Xylose is transformed by xylose isomerase into xylulose and consequently converted by xylulokinase into xylulose 5-phosphate, entering the pentose phosphate pathway. Glycerol is transported through the membrane by glycerol facilitator (GlpF) and metabolized by glycerol kinase (GlpK) into glycerol-3-phosphate (G3P), which is converted by glycerol-3-phosphate dehydrogenase (GlpD) into dihydroxyacetone phosphate that is channeled into glycolysis. The substrate gluconate is phosphorylated by gluconokinase into gluconate-6-phosphate, which can be channeled into the pentose phosphate pathway or ED pathway. Most of the genomes of Paraburkholderia and Burkholderia strains reported for P(3HB) production (Table 5.1) possess the enzymes depicted in Figure 5.4.
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).
Algal Biofuel: A Promising Alternative for Fossil Fuel
Published in Maniruzzaman A. Aziz, Khairul Anuar Kassim, Wan Azelee Wan Abu Bakar, Aminaton Marto, Syed Anuar Faua’ad Syed Muhammad, Fossil Free Fuels, 2019
Hoofar Shokravi, Zahra Shokravi, Maniruzzaman A. Aziz, Hooman Shokravi
Lipid biosynthesis in microalgae mainly takes place through both fatty acid synthesis and TAG synthesis, which occur in the chloroplast and the endoplasmic reticulum, respectively. The fatty acid and TAG biosynthetic pathways have been fully characterized in microalgae. Fatty acid synthesis is performed by two different enzymatic systems including acetyl-CoA carboxylase (ACCase) and fatty acid synthase (FAS). The first step for the biosynthesis of fatty acid is synthesized under the catalysis of ACCase, which transforms acetyl-CoA to malonyl-CoA. The second step is catalyzed by FAS complex. The malonyl moiety is transferred to acyl carrier protein (ACP) and makes malonyl-ACP, which is added to another acyl-ACP to form an acyl chain with two carbons longer. Further reactions lead to a saturated and unsaturated acyl chain with acyl carrier protein. When the chain reaches the appropriate length, acyl carrier protein is removed from fatty acid, yielding the complete fatty acid. Furthermore, the synthesis of TAG is performed by four enzymes, including glycerol-3- phosphate dehydrogenase (GPDH), lysophosphatidic acyltransferase (LPAAT), diacylglycerol acyltransferase (DGAT) and glycerol-3-phosphate acyltransferase (GPAT). Therefore, the overexpression of these genes has been used as a technique to promote lipid content [58–60].
New approaches towards the discovery and evaluation of bioactive peptides from natural resources
Published in Critical Reviews in Environmental Science and Technology, 2020
Nam Joo Kang, Hyeon-Su Jin, Sung-Eun Lee, Hyun Jung Kim, Hong Koh, Dong-Woo Lee
Accumulation of excess body fat causes obesity, exerting a negative effect on health. The amount of adipose tissue tightly regulated by adipogenesis in pre-adipocyte cells, the best-characterized model for studying adipogenesis (Aoyama, Fukui, Takamatsu, Hashimoto, & Yamamoto, 2000). Glycerol-3-phosphate dehydrogenase (GPDH), a key enzyme in glycolysis, is linked to phospholipid and triglyceride biosynthesis (Harding, Pyeritz, Copeland, & White, 1975; Tsou, Lin, Lu, Tsui, & Chiang, 2010). Because suppression of GPDH activity inhibits differentiation and reduces lipid accumulation in pre-adipocyte cells, the anti-adipogenic effects of BPs can be evaluated by measuring the activity of this enzyme (Hirai, Yamanaka, Kawachi, Matsui, & Yano, 2005). In addition, saturated fatty acids from acetyl-CoA and malonyl-CoA are synthesized endogenously by fatty-acid synthase (FAS), which is involved in adipogenesis (Leibundgut, Maier, Jenni, & Ban, 2008). Some hydrolyzed proteins can inhibit FAS activity, thereby controlling cell differentiation and lipid accumulation (Gonzalez-Espinosa de los Monteros, Ramon-Gallegos, Torres-Torres, & Mora-Escobedo, 2011; Martinez-Villaluenga, Dia, Berhow, Bringe, & Gonzalez de Mejia, 2009).