Recycling, sugar nucleotide systems

Other than the recycling system using p)nuvate kinase and phosphoenolpyruvate (PEP) (Fig. 1), sugar nucleotides recycling systems using sucrose synthetase (30,31) (Fig. 2) or an inexpensive kinase system with polyphosphate kinase and polyphosphate were also developed (32). 

Sugar nucleotide recycling systems attempt to take advantage of the efficiency of biosynthetic pathways in enzymatic synthesis. In biological systems, simple monosaccharides are the precursors to sugar nucleotides (Figure 2) [6b]. 

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