Carbohydrate diversity

Both chemo- and bioenzymatic methods have already yielded considerable carbohydrate diversity around different skeleta. Glycosylation of novel positions and alteration of sugar biosynthetic pathways were realized for different classes of NPs. Several issues have to be solved to tap more fully into the potential of the described glycodiversification techniques. 

Holemann A, Seeberger PH. Carbohydrate diversity synthesis of glycoconjngates and complex carbohydrates. Cnrr Opin Biotech-nol 2004 15 615-622. 

A. Holeman, P.H. Seeberger, Carbohydrate diversity synthesis of glycoconjugates and complex carbohydrates, Curr. Opin. Biotechnol. 2004, 15, 615-622. 

Holemann A, Seeberger P H (2004). Carbohydrate diversity Synthesis of glycoconju-gates and complex carbohydrates. Curr. Opin. Biotech. 15 615-622. 

Das I, Pal TK, Suresh CG, Pathak T (2007) Diastereoselective C-C bond formation at C-5 of vinyl sulfone-modified hex-5-enofuranosyl carbohydrates diversity-oriented synthesis of branched-chain sugars and beyond. J Org Chem 72 5523-5533... 

Exploring Carbohydrate Diversity through Automated Synthesis... 

It was known as early as 1927 that the adrenal glands of mammalian species secrete a series of substances essential to the survival of the individual. The hormonal nature of these secretions was suggested by the observation that extracts of the adrenal gland and more specifically of the outer portion of that organ (cortex) would ensure survival of animals whose adrenals had been excised. By 1943 no fewer than 28 steroids had been isolated from adrenal cortical extracts. These compounds were found to be involved in the regulation of such diverse and basic processes as electrolyte balance, carbohydrate metabolism, and resistance to trauma, to name only a few. 

We ve now covered two of the four major classes of biomolecuies—proteins and carbohydrates—and have two remaining. We ll cover lipids, the largest and most diverse class of biomolecules, in this chapter, looking both at their structure and function and at their metabolism. 

A more general access to biologically important and structurally more diverse aldose isomers makes use of ketol isomerases for the enzymatic interconversion of ketoses to aldoses. For a full realization of the concept of enzymatic stereodivergent carbohydrate synthesis, the stereochemically complementary i-rhamnose (Rhal EC 5.3.1.14) and i-fucose isomerases (Fuel EC 5.3.1.3) from E. coli have been shown to display a relaxed substrate tolerance [16,99,113,131]. Both enzymes convert sugars and their derivatives that have a common (3 J )-OH configuration, but may deviate in... 

Glycoproteins occur in most organisms, from bacteria to humans. Many vimses also contain glycoproteins, some of which have been much investigated, in part because they are very suitable for biosynthetic studies. Numerous proteins with diverse functions are glycoproteins (Table 47-1) their carbohydrate content ranges from 1% to over 85% by weight. 

Glycoproteins are widely distributed proteins— with diverse functions—that contain one or more covalently linked carbohydrate chains. 

A wide diversity of herbal remedies have purported abilities to stimulate defense functions. Complexes of carbohydrate and lignin, which are present in some herbs, modulate enteric immune functions (Kiyohara et al, 2000), and the changes in cytokine secretion (Matsumoto and Yamada, 2000) can trigger systemic responses. The polysaccharides present in other herbal medicines augment production of immunoglobulin (Ig) A by the Peyer s patches in the small intestine (Sakushima et al, 1997 Yu et al, 1998). The responses of the enteric immune system to lectins are variable (Pusztai 1993), and can elicit systemic responses (Lavelle et al, 2000). Other phytochemicals provide protection by inducing detoxification pathways in mucosal cells (Williamson et al, 1998). 

The complex cascades that comprise the inflammatory reaction are designed primarily to limit tissue damage and prevent or inhibit infection. ROMs play a critical role in both these beneficial processes. However, high level fluxes of toxic free radicals are capable of causing damage to diverse biomolecules, including lipids, proteins, DNA and carbohydrates (discussed below). 

The chemical composition of the natural resins is very diverse, and their molecular structure may be highly complex most resins of vegetable origin, however, are chemically related to the carbohydrates. Dry vegetable resins... 

Biochemical tests are usually performed after pure cultures have been obtained. The standard indole, methyl red, Voges-Proskauer, citrate, and litmus milk tests may be used to show important physiological characteristics. To study the functional diversity of bacteria, the utilization of carbohydrates, amines, amides, carboxylic acids, amino acids, polymers, and other carbon and nitrogen sources can be tested.28 Dilution-based most-probable number (MPN) techniques with phospholipid fatty acids as biomarkers have been employed for studying different bacterial species in lakes.40 The patterns of antibiotic resistance in bacteria isolated from natural waters have been useful for identifying sources of water pollution.34... 

As detailed structural information is obtained from a greater diversity of parasitic nematodes it is expected that the occurrence of stage-specific carbohydrate antigens, and therefore stage-specific glycosyl transferase activities, will be identified as a common characteristic. 

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