Regulation of poly-β-hydroxybutyrate biosynthesis by nicotinamide nucleotide in Alcaligenes eutrophus |
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Authors: | In Young Lee Mi Kyoung Kim Ho Nam Chang Young Hoon Park |
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Affiliation: | Korea Research Institute of Bioscience and Biotechnology, KIST, PO Box 115, Taedok Science Town, Taejon, South Korea; Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Taedok Science Town, Taejon 305-701, South Korea |
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Abstract: | Abstract Poly-β-hydroxybutyrate biosynthesis was studied in Alcaligenes eutrophus under various nutrient-limiting conditions. When the cells were cultivated in nitrogen-limited media, both the levels of NAD(P)H and the ratios of NAD(P)H/NAD(P) were higher than those under nitrogen-sufficient conditions. The specific poly-β-hydroxybutyrate production rate was found to increase with the values of both NADH/NAD and NADPH/NADP, indicating that poly-β-hydroxybutyrate synthesis is directly regulated by the ratios of nicotinamide nucleotides. The effects of nicotinamide nucleotides on poly-β-hydroxybutyrate biosynthesis was investigated with regard to enzyme kinetics. Citrate synthase activity was significantly inhibited by NADH and NADPH, indicating that poly-β-hydroxybutyrate accumulation could be enhanced by facilitating the metabolic flux of acetyl-CoA to poly-β-hydroxybutyrate synthetic pathway. It was also found that cellular NADPH was a limiting substrate for NADPH-linked reductase, controlling the overall biosynthetic activity of poly-/3-hydroxybutyrate in this strain. |
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Keywords: | Poly-β-hydroxybutyrate biosynthesis Regulation Nicotinamide nucleotide Alcaligenes eutrophus |
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