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Medium Design for Cell Culture Processing
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
Galactose and fructose do not get phosphorylated at their C6 position and enter the glycolysis pathway directly. They can serve as the main hexose source for cells through alternative entry points to glycolysis. Galactose is phosphorylated at C1 to become galactose 1-phosphate, and then through a transferase and an epimerase catalyzed reaction it becomes glucose 1-phosphate, which is converted to glucose 6-phosphate. Fructose, once in the cytosol, is converted to fructose 1-phosphate and split into dihydroxyacetone 3-phosphate and glyceraldehyde by aldolase. Both are then converted to glyceraldehyde 3-phosphate and enters glycolysis (Figure 7.4).
Glycolysis and Fermentation
Published in Jean-Louis Burgot, Thermodynamics in Bioenergetics, 2019
Fructose and galactose can enter into the glycolytic chain. fructose enters into glycolytic chain through the formation of fructose-1-phosphate with the aid of fructokinase. Then, the fructose-1-phosphate is cut into two parts: the glyceraldehyde plus the dihydroxyacetonephosphate. Here, again, there is a cleavage by retroaldolisation catalysed by a specific fructose-1-phosphate aldolase. The glyceraldehyde is then phosphorylated in glyceraldehyde-3-phosphate by a triose kinase. Hence, it can enter into the glycolysis: galactose enters through the glycolysis chain once it is transformed into glucose-6-phosphate by a process in four steps. There is first the transformation galactose → galactose-1-phosphate: galactose + ATP→galactokinasegalactose-1-phosphate + ADP + H+Secondly, the galactose-1-phosphate reacts with the uridine diphospho-glucose (UDP-glucose) and gives the UDP-galactose and the glucose-1-phosphate. The reaction is catalyzed by the galactose-1-phosphate uridyl transferase. Transformation of galactose-1-phosphate into glucose-1-phosphate.
Effects of the carbon source and the interaction between carbon sources on the physiology of the industrial Saccharomyces cerevisiae CAT-1
Published in Preparative Biochemistry & Biotechnology, 2020
Valkirea Matos Nascimento, Gustavo Graciano Fonseca
The low specific growth rates in galactose may be the result of evolutionary variations, due to the lower availability of sugar in the environment. As the glucose substrate is abundant, several genes encode glucose-carrying proteins, but only galactose permease (GAL2) is capable of transporting galactose with an affinity comparable to these carriers.[19] Another limiting step is the accumulation of metabolic intermediates of the galactose metabolism (galactose-1-phosphate and glucose-1-phosphate).[20] They may inhibit flow through the Leloir pathway, decreasing the rate of absorption of galactose by yeast.[21,22]
Metabolomics profiling of valproic acid-induced symptoms resembling autism spectrum disorders using 1H NMR spectral analysis in rat model
Published in Journal of Toxicology and Environmental Health, Part A, 2022
Hyang Yeon Kim, Yong-Jae Lee, Sun Jae Kim, Jung Dae Lee, Suhkmann Kim, Mee Jung Ko, Ji-Woon Kim, Chan Young Shin, Kyu-Bong Kim
Galactosemia is a similar symptom detected in ASD, which is an inborn error of metabolism produced by a deficiency in one of three enzymes; uridine diphosphate galactose 4-epimerase, galactokinase, or galactose-1-phosphate uridyl-transferase (GALT), resulting in increased galactose and galactonate levels in urine (Rubio-Gozalbo et al. 2019; Wehrli et al. 1997). The expression of these galactosemia-related enzymes was reported in ASD by Rubio-Gozalbo et al. (2019).