Study On Enzymatic Synthetic Process Of Inositol From Glucose

Myo-inositol(inositol),also called cyclohexanhexol,is the most common and bioactivecompound in nature.Inositol is widely distributed in plants and animals as their growth factor and plays an important role in cosmetic,pharmaceutical and functional food industries.In addition,The global market size of inositol is approximately 50 million tons and the price of is 80 thousand yuan per ton.Now most inositols are produced through acid hydrolysis of phytate,which is extracted from bran and seeds by a series of purification steps at high temperature and pressure.This production method is the main way to obtain inositol with many limitations,including complex process,a high cost of purification,serious chemical pollution and low efficiency.Therefore,the development of an efficient,ecofriendly and economical method to produce inositol is needed.To solve the abovementioned problems,we created an economical and efficient way for the production of inositol through trienzymatic cascade reaction.In this study,enzymes were obtained by employing the efficient Escherichia coli.expressing system,and the enzyme activity was further improved by high cell density fermentation.Using this enzymatic synthetic process for inositol production,we increased the conversion rate and shortened the the production time.We cloned and expressed three enzymes from different origins.By applying the Escherichia coli.high efficiency expressing system constructed in our lab,we screened the vectors and chose a proper pasmid to efficiently express the enzymes.By optimizing the fermentation conditions and screening vectors wecan produce soluble enzymes.The conversion for the synthesis of inositol from glucose in one vessel was developed.And this conversion required three enzymes: polyphosphste glucokinase(PPGK)from Arthrobacter sp.Inositol-1-phosphate Synthase(IPS)from Trypanosoma brucei.and Inositol monophosphatase(IMP)from Escherichia coli.In this research,inositol was produced from glucose by trienzymatic system of PPGK,IPS,IMP with a conversion rate of 70%.It was noted that the biosynthesis of inositol from glucose without ATP is an efficient and environmentally friendly method comparing with the current methods.However,high concentration of sodium hexametaphosphate and phophate showed inhibitory effect on the IPS activity which limited the inositol production.Therefore,to prevent the inhibition of high concentration of sodium hexametaphosphate,the one-pot two-step enzymatic reaction was implemented and consequently,a conversion ratio of 90% from glucose to inositol was achieved.These results suggest that this trienzymatic cascade reaction that improves the yieldof insitol and production efficiency is a promising approach for the synthesis of inositol from glucose.Our study provides a promising approach for the synthesis of inositol that is the first trienzymatic transformation of inositol from glucose.