Figure 2: Complete oxidation of maltodextrin based on a synthetic enzymatic pathway.
From: A high-energy-density sugar biobattery based on a synthetic enzymatic pathway
(a) Schematic of the complete oxidation of maltodextrin via the synthetic catabolic pathway. The enzymes are as follows—1: αGP, α-glucan phosphorylase; 2: PGM, phosphoglucomutase; 3: G6PDH, glucose-6-phosphate dehydrogenase; 4: 6PGDH, 6-phosphogluconate dehydrogenase; 5: RPI, ribose-5-phosphate isomerase; 6: Ru5PE, ribulose-5-phosphate 3-epimerase; 7: TK, transketolase; 8: TAL, transaldolase; 9: TIM, triosephosphate isomerase; 10: ALD, aldolase; 11: FBP, fructose-1,6-bisphosphatase; 12: PGI, phosphoglucose isomerase; and 13: DI, diaphorase. The key metabolites are glucose-1-phosphate (g1p), glucose-6-phosphate (g6p), 6-phosphogluconate (6 pg) and ribulose-5-phosphate (ru5P). Pi, inorganic phosphate; VK3, vitamin K3. (b) Profiles of power density versus current density for the sugar biobattery using only G6PDH, G6PDH and 6PGDH, or the entire pathway. The experimental conditions were 100 mM HEPES, pH 7.5, buffer containing 0.1 mM maltodextrin, 4 mM NAD+, 100 mM HEPES, pH 7.5, 4 mM sodium phosphate, 10 mM MgCl2, 0.5 mM MnCl2, 5 mM DTT and 0.5 mM thiamine pyrophosphate at room temperature. The enzyme loading conditions are shown in Supplementary Table S1. (c) Profiles for current generation and cumulative Faraday efficiency. The experimental conditions were 100 mM HEPES, pH 7.5, buffer containing 0.1 mM of maltodextrin, 10 mM MgCl2, 0.5 mM MnCl2, 4 mM NAD+, 4 mM sodium phosphate, 5 mM DTT, 0.5 mM thiamine pyrophosphate, 50 mg l−1 kanamycin, 40 mg l−1 tetracycline, 40 mg l−1 cycloheximide, 0.5 g l−1 sodium azide, 1 g l−1 BSA and 0.1% Triton X-100.
