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Cellulose, the Main Component of Biomass
Published in Jean-Luc Wertz, Magali Deleu, Séverine Coppée, Aurore Richel, Hemicelluloses and Lignin in Biorefineries, 2017
Jean-Luc Wertz, Magali Deleu, Séverine Coppée, Aurore Richel
UDPGlc can be formed along a pathway in which: α-D-glucose is phosphorylated to α-D-glucose-6-phosphate by the enzyme glucokinase.α-D-glucose-6-phosphate is isomerized to α-D-glucose-1-phosphate by the enzyme phosphoglucomutase.α-D-glucose-1-phosphate is converted to α-linked UDPGlc by the enzyme UDPGlc pyrophosphorylase.41,42
Applications in Biology
Published in Gabriel A. Wainer, Discrete-Event Modeling and Simulation, 2017
We also considered the formation of UDP-glucose, which can be attached to glucose chains that can be acted upon by glycogen synthesis. Glucose enters the cells by facilitated diffusion, and then the cell modifies glucose by phosphorylation, as shown in Figure 8.11. Glucose-6-phosphate is used in the synthesis of glycogen: glucose-6-phosphate is first isomerized to glucose-1-phosphate by the enzyme phosphoglucomutase, as seen in Figure 8.12. UDP-glucose has the ability to attach its glucose part to glucose chains. This new chain can be acted upon during glycogen synthesis, as seen in Figure 8.13. Figure 8.14 shows this process in our CD++ simulation.
Cellulose – A Sustainable Material for Biomedical Applications
Published in Ashwani Kumar, Mangey Ram, Yogesh Kumar Singla, Advanced Materials for Biomechanical Applications, 2022
N. Vignesh, K. Chandraraj, S.P. Suriyaraj, R. Selvakumar
The synthesis of BC proceeds through a bottom-up approach wherein the glucose monomers taken up by the bacteria are assembled into cellulose through metabolic pathways inside the cell (Figure 4.1b). Initially, glucose is phosphorylated to glucose-6-phosphate by glucokinase. The isomerization of glucose-6-phosphate to glucose-1-phosphate is catalyzed by phosphoglucomutase. Further, glucose-1-phosphate is converted into uridine diphosphate glucose (UDPG) by UDPG pyrophosphorylase. The polymerization of glucose into cellulose is finally catalyzed by cellulose synthase through the formation of linear β-1,4-glucan chains [30]. The synthesized cellulose present in the form of protofibrils is secreted across the cell wall through transporters (Figure 4.1c). In the extracellular medium, the secreted protofibrils aggregate into microfibrils, which further organize into a desired nanostructure like a pellicle or mat depending on the culture condition [25].The production of BC is simple, as it requires optimum physical conditions like pH, temperature and aeration for the growth of the bacterial strain. Moreover, the secreted BC is treated with alkali to produce cellulose polymorph II for increasing the pore size, surface area and elasticity of the material [37]. Besides, the elevated porosity of BC facilitates its application as a precursor material for aerogel preparation (Figure 4.1d). To improve the properties of BC, in situ modification of its structure has been reported in many studies. Unlike an external chemical treatment, in situ modification refers to an alteration in the chemical composition of BC through the supplementation of additives in the growth medium. As a result, the desired components are incorporated into the structure of BC during microbial synthesis [38]. BC conjugates produced using additives such as polyvinyl alcohol, hydroxyapatite, chitosan, heparin and dextrin have been used for developing cardiovascular soft tissue, bone regeneration scaffold, antimicrobial membrane, anticoagulant wound dressing material and blood transfusion membrane respectively [29]. Eventhough BC is associated with intriguing properties and environmentally friendly production, the requirements of a large vessel, continuous aeration and longer process time are the major limitations hindering the commercial feasibility (Table 4.2).
Fusion of cellobiose phosphorylase and potato alpha-glucan phosphorylase facilitates substrate channeling for enzymatic conversion of cellobiose to starch
Published in Preparative Biochemistry & Biotechnology, 2022
Xinyu Liu, Huawei Hou, Yapeng Li, Sen Yang, Hui Lin, Hongge Chen
All chemicals were of reagent grade or higher. Cellobiose, maltodextrin (degree of polymerization (DP) 4.0–7.0), phosphoglucomutase (PGM), glucose-6-phosphate dehydrogenase, nicotinamide adenine dinucleotide phosphate (NADP+), glucose1,6-bisphosphate, and triethanolamine were purchased from Sigma-Aldrich (St. Louis, USA). The restriction enzymes and Phusion DNA polymerase were obtained from New England BioLabs. DNA synthesis and sequencing were performed by Genewiz Inc., China.
Cyanobacteria mediated heavy metal removal: a review on mechanism, biosynthesis, and removal capability
Published in Environmental Technology Reviews, 2021
Abdullah Al-Amin, Fahmida Parvin, Joydeep Chakraborty, Yong-Ick Kim
Wild type cyanobacteria may not be an ideal organism for all types of heavy metal ion removal operations. Every species has some limitations in biosorption [47]. To combat all of these challenges, engineered cyanobacteria may be a good alternative for ideal heavy metal removal operations. Genetic modification enhances anionic moiety in cell surface and alteration of chemical compounds for optimum heavy metal ion adsorption in cell surface [38]. Cyanobacterial EPS is highly complex in nature. Though knowledge in EPS biosynthesis is still insufficient, EPS synthesis pathway engineering may provide insights for optimizing EPS production, which may enhance anionic moiety in the cell surface. The following three approaches can genetically modify the EPS: EPS synthesis is carbon and energy-demanding process. Expressing BicA transporter in Synechocystis sp. strain PCC6803, resulted in enhancing CO2 uptake, faster growth of the cell, and increase of EPS production [67]. Another approach to enhance carbon availability is by reducing carbon sink and other competitive pathways, for example, sucrose, glycosylglycocerol, and glycogen. This approach may shift the carbon sink toward polysaccharide production [58].Sufficient sugar nucleotides can induce high EPS production. Performing metabolism engineering enhances the expression level of enzymes (phosphoglucomutase, UDP-glucose pyrophosphorylase, UDP-glucose dehydrogenase, and UDP-galactose-4-epimerase), responsible for supplying nucleotide sugar precursor might enhance EPS production [68].Assemblance of monosaccharide's repeated unit into polysaccharide may be achieved by overexpressing native glycosyltransferase or recombining heterologous glycosyltransferase genes [69]. And these polysaccharides will be transported outside the cell as EPS.