ISSN:0570-0833    

DOI:10.1002/anie.199503711

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractVitamin B12is an essential vitamin for human health, and lack of it leads to pernicious anemia. This biological activity has attracted intense interest for some time; in addition, the complex architecture of the B12molecule has fascinated chemists and biochemists since its discovery as the first natural organocobalt complex and the establishment of its structure by X‐ray analysis. The organic ligand surrounding the cobalt displays many stereogenic centers along its periphery carrying reactive functional groups. This complexity led vitamin B12to be rightly regarded as an extreme challenge to the synthetic chemist. Yet microorganisms achieve this synthesis in vivo with complete control of regio‐ and stereochemistry. How do they do it? This review tells the full remarkable story. Success in unraveling this biosynthetic puzzle resulted from a collaborative effort by biologists and chemists using the full range of methods available from their disciplines–from genetics at one end of the spectrum to synthesis and NMR spectroscopy at the other. This work can act as a guide for future research on the biosynthesis of yet more complex natural subst

ISSN:0570-0833    

DOI:10.1002/anie.199503831

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractCarbohydrates on cell surfaces are information molecules. Although only seven or eight monosaccharides are commonly used as building blocks in mammalian systems, the multifunctionality of these monomers can lead to the assembly of an immense variety of complex structures. Millions of different tetrasaccharide structures, for example, can be constructed from this small number of building blocks, if branching, the stereochemistry of glycosidic linkages, and the modification of hydroxyl and amino groups are taken into consideration. Oligosaccharides therefore represent an effective class of biomolecules that code for a vast amount of information required in various biological recognition processes, such as intercellular communication, signal transduction, cell adhesion, infection, cell differentiation, development and metastasis. The pace of development of pharmaceuticals based on carbohydrates has, however, been slower than that based on other classes of biomolecules. Part of the reason is the lack of technologies for the study of complex carbohydrates. There is no method to amplify oligosaccharides for sequence analysis. There is no machine available for automated synthesis of oligosaccharides. In addition, the possibly poor bioavailability and difficulties in the large‐scale synthesis of carbohydrates have undoubtedly contributed to this slow pace. The enzymatic and chemoenzymatic methods, especially those based on aldolases and glycosyltransferases, described here appear to be useful for the synthesis of mono‐ and oligosaccaharides and related molecules. Further advances in glycobiology will probably lead to the development of new technologies for the study of carbohydrate recognition and for the synthesis of bioactive carbohydrates and mimetics to control the recognition proces

ISSN:0570-0833    

DOI:10.1002/anie.199504121

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504331

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504361

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504391

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504411

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504431

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504461

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199504481

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY