Synthesis Of Sialyloligosaccharides Catalyzed By Whole Celland Sialyltransferases

Sialyloligosaccharides and their derivatives are widely distributed in various kinds of biological tissue, they have important biological functions. Nowdays, the sialyloligosaccharides preparation technology is complex process, low production rate and high cost. It is difficult to meet the needs of the market and the scientific research.This research based on the E.coli K-12,which can product sialic acid of high yields,constructed by Chinese academy of sciences institute of microbiology.Combining the sialic acid synthetase(NmCSS) and sialic acid transferase(Pm2,3ST or Pd2,6ST),established the whole cells joint double enzyme catalysis synthesize sialic acid oligosaccharides and their derivatives in an efficient synthesis system, mainly including the following three aspects of content :Firstly, using the method of chemical synthesis, synthesis of a series of GlcNAc derivatives.Owing to the GlcNAc sugar ring containing reactive group,which need protection and deprotection strategy, selectively modifing some groups, the method is relatively simple, and can get the target compound on high yield rates.Secondly, using the E.coli K-12,which constructed by the Chinese academy of sciences institute of microbiology can synthesize sialic acids and their derivatives of high yield in one step.The engineering bacteria can highly express enzyme catalytic reaction of enzyme(ATP synthetase, GNE, Neu5 Ac aldolase), and these enzymes have a great deal of tolerance of the substrates. Transforming many kinds of monosaccharide into special sialic acids and their derivatives.Thirdly,using the double enzyme(CMP- sialic acid synthetase NmCSS, sialic acid transferase Pm2,3ST or Pd2,6ST), sialyloligosaccharides and their derivatives was synthesized by one-step method efficiently, the two enzymes also have great tolerance to donors and receptors, they can connect a lot of sialic acid derivatives and receptor of sugar chain molecules together, enzymatic catalysis method can effectively control the stereochemical structure of the sialyloligosaccharides.This dissertation combined the whole-cell catalysis, chemical synthesis and enzyme catalysis, developing a new strategy synthesis of sialic acid oligosaccharides and their derivatives. Smoothly finish this subject not only can obtain a variety of sialic acid derivatives and sialic acid oligosaccharide derivatives,but also provide a new reference for the use of multidisciplinary to solve glycoscience problem in the field of science.