초록
<P><B>Abstract</B></P> <P>In vitro cascade catalysis using enzyme-based system is becoming a promising biomanufacturing platform for biofuels and biochemicals production. Glutathione is a pivotal non-protein thiol compound and widely applied in food and pharmaceutical industries. In this study, glutathione was synthesized by a bifunctional glutathione synthetase together with a thermophilic ATP regeneration system through a two-enzyme cascade in vitro. Four bifunctional glutathione synthetases from <I>Streptococcus sanguinis</I>, <I>S. gordonii</I>, <I>S. uberis</I> and <I>Bacillus cereus</I> were applied for glutathione synthesis. The bifunctional glutathione synthetase from <I>S. sanguinis</I> was selected and coupled with the polyphosphate kinase from <I>Thermosynechococcus elongatus</I> BP-1 for regenerating ATP to produce glutathione in one pot. In the optimized system, 28.5mM glutathione was produced within 5h due to efficient ATP regeneration from low-cost polyphosphate. The yield based on added <SMALL>L</SMALL>-cysteine reached 81.4% and the productivity of glutathione achieved 5.7mM/h. The one-pot system indicated a potential biotransformation platform for industrial production of glutathione.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The availability of ATP is a key issue in GSH biosynthesis economically. </LI> <LI> A polyphosphate kinase preferred short-chain polyphosphate was applied. </LI> <LI> GSH biosynthesis and ATP regeneration were coupled together in one pot and efficiently formed GSH with polyP. </LI> <LI> The yield of 81.4% was achieved and the productivity was 5.7mM/h. </LI> </UL> </P>