Glycoside is a compound formed by condensation of the hemiacetal hydroxyl group of sugar or sugar derivative with another non-sugar substance. Natural glycosides are mainly derived from secondary metabolites of plants. For their own defense needs, plants synthesize a large number of glycosides, providing humans with abundant resources for research, development and production of drug candidate compounds. Glycoside compounds have a variety of important pharmacological activities such as dispelling rheumatism, antibacterial, anti-inflammatory, anti-tumor, immune regulation, improving respiratory and digestive tracts, and more than 70% of the drugs currently on the market are related to glycoside compounds. With the rise of sugar engineering, as well as the development of separation, purification and identification technology, the research on the effective components of glycosides in plants will be more in-depth and the application will be more extensive. According to different structures, glycosides can be classified in many ways. According to the difference of glycoside atoms, it can be divided into oxyglycosides, thioglycosides, carbon glycosides and azaglycosides, of which oxyglycosides are the most common. The structural diversity of glycosides produces a variety of pharmacological activities. The pharmacological activity of glycosides is not only related to the aglycone, but also closely related to the sugar chain part. The monosaccharide composition of the sugar chain in the glycoside, the configuration of the glycosidic bond, and the way of glycosyl connection all affect the activity and metabolic pathways of the glycoside. Some glycosides are hydrolyzed to generate aglycones and produce better pharmacological activities, such as quercetin and geni equality. Modifying the sugar chain part of the glycoside molecule and studying its structure-activity relationship is of great significance for the discovery of new types of glycoside drugs. Chemical methods such as acid or base catalysis can be used to hydrolyze sugar chains, and biological methods such as microorganisms and enzyme catalysis can also be used to hydrolyze sugar chains. Chemical hydrolysis of glycosides sometimes produces more by-products, and at the same time easily causes environmental pollution. Biological methods may overcome these problems. Therefore, glycoside hydrolase is considered as a potentially effective tool for preparing active glycosides and aglycones. This article systematically summarizes the research progress on the conversion of glycoside hydrolases to produce active glycosides and aglycons.
Glycoside hydrolase is a true hydrolase and does not require any coenzymes and cofactors. There are many glycoside hydrolases, which are widely present in bacteria, fungi, plant seeds and animal organs. They can be divided into different families based on the similarity of amino acid residue sequences and structures. At present, 145 glycoside hydrolases families have been reported. The properties and functions of glycoside hydrolases have always been the focus of research in the field of glycobiology. The research on glycoside hydrolase in my country began in the late 1950s. Academician Zhang Shuzheng and others analyzed and compared the composition of the amylase system of different Aspergillus in the alcohol industry. The amylase was separated and determined by paper electrophoresis in China. In 1966, 3 strains of Rhizopus producing high-activity amyloglucosidase hydrolase were screened out from 150 strains of Rhizopus, and their enzyme activity properties were preliminary explored. Beginning in the 1980s, Academician Zhang Shuzheng carried out basic and applied research on various glycosidases, and vigorously advocated frontier projects in glycobiology and glycoengineering. As one of the founders of glycobiology, Academician Zhang Shuzheng has been committed to the research of microbial biochemistry and glycobiology for a long time, and has made remarkable achievements in the structure and function of glycosidases, glycobiology and glycobiology engineering, and has contributed to our country The development of enzyme preparation industry and enzymology has made a foundational contribution.
As the importance of carbohydrate compounds in the field of biology has become more and more prominent, the research and application of glycoside hydrolases have also attracted more and more attention. At present, glycoside hydrolases are mainly obtained from microorganisms or animals and plants through separation, purification and molecular cloning techniques. Yu Wei et al. screened the Enterobacter cloacae YW2112 strain from soil microorganisms. The glycosidase isolated and purified from it can specifically hydrolyze the glycosidic bond between the ceramide and oligosaccharide chain in the ganglioside. An important tool for functionality. Zhang Shuzheng and others constructed β-amylase recombinantly from the whole genome DNA library of Bacillus megaterium. After comparison and analysis of amino acid sequence, it was found that the enzyme consists of signal peptide domain, glycosyl hydrolase catalytic domain and starch binding domain in turn. composition. With the continuous development of molecular biology technology, random mutation and directed evolution are widely used in improving glycoside hydrolases. Tang Shuangyan from the Institute of Microbiology, Chinese Academy of Sciences, etc. improved the thermal stability of Bacillus glucoamylase through DNA recombination technology, and predicted the mechanism of improving the thermal stability of the mutant enzyme. At present, the preparation and industrial application of glycoside hydrolases have achieved remarkable results. Glycoside hydrolase is easily obtained through fermentation. With the rapid development of genetic engineering and protein engineering, recombinant glycoside hydrolase has been widely used due to its high expression and easy purification. The enzymatic conversion process has mild conditions, good specificity, high yield, and environmental protection. Therefore, glycoside hydrolase has become an effective tool for the conversion and preparation of active glycosides and aglycones.
Glycosides have a variety of biological activities such as anti-inflammatory, anti-oxidant and anti-tumor, and have good prospects for the development of medicines, health products and cosmetics. With the advancement of modern biotechnology, extraction, separation, and analysis and testing methods have been continuously improved. The development of enzymology has opened up a wide range of applications of biotransformation technology, and the use of enzymes to convert glycosides has attracted more and more attention. The preparation of new glycosides and aglycons by glycoside hydrolase will change the biological activity of glycosides and provide abundant resources for medicines and health foods. At present, the research on the catalytic mechanism of enzymes is relatively weak, especially the analysis of the three-dimensional structure of the enzyme at the molecular level, and the study of the relationship between the structure of the enzyme and its selectivity are few and not in-depth. Modern biotechnology such as molecular biology and structural biology will gradually solve these scientific problems, and biotransformation to prepare new glycoside compounds will be more and more widely used in industrial and agricultural production.