Chain glycoside

In the field of polymer science, the most extensively used transferase is phosphorylase (systematic name (1 4)-a-D-glucan phosphate a-D-glucosyltransferase EC 2.4.1.1). Although this enzyme is responsible for the depolymerization of linear a-( 1 4) glycosidic chains in vivo it can also be used to synthesize linear a-( 1 4) glycosidic chains (amylose) in vitro. 

In some cases where enzymes have a poor degree of surface amino groups, the covalent linkage can be established through the glycosidic chains by periodate oxidation of enzyme with subsequent coupling to activated nylon (Lopez, Braun Klein, 1996). 

O-linked glycoside chain with chondroitin sulphate -11.7 kDa... 

Fig. 2. Glycoside chains and the Kunitz domains. Amino acid and glycoside sequences for the two Kunitz-binding domains of Bik are shown. C-C across a chain indicates a cross-link. Predicted fragmentation points for Bik due to trypsin exposure are shown by lines with black dots. The aprotinin-matching peptides of each Kunitz domain are shown by a darkened circle. The first peptide of aprotinin is indicated as Aprol. The X-ray structure-predicted touch points between Bik and trypsin are marked. The predicted PI peptide of the active inhibitory site sequence is indicated as well.

The complete sequences of the carbohydrate chains of Bik are known to change during disease progression [31-33]. Both O- and N-linked glycoside chains are connected to Bik in domain I (Fig. 2). A key feature of the O-linked glycoside is the sulfated chondroitin chain. The O-linked chondroi-tin sulfate glycoconjugate is essential for cell membrane stability and is also involved in cell membrane binding. 

Polymers of monosaccharides may be either of the homo- or hetero-type. When the number of units in a glycosidic chain is in the range of 2 to 10, the resulting compound is an oligosaccharide. More than 10 units are usually considered to constitute a polysac-... 

Figure 38 Amino acid sequences of systemines (a-c), RALF (d), and AtPep (e). P, hydroxyprolines with glycoside chain.

Unfortunately, a universal method for selective O-glycosidation does not yet exist. In fact, even small changes of reaction conditions, nature of donor, acceptor or promoter can dramatically compromise the success of the selected glycosidation protocol. However well-adaptable procedures are nowadays available, affording O-glycoside chains with a remarkable a/p selectivity. 

In solid phase synthesis (SPS) of biopolymers, the peptide/nucleotide/glycoside chain is assembled in the nsnal manner (conventional approach) from the C-/3 -/NR-end. The first monomer unit of the biopolymer to be synthesized is connected via its car-boxyl/hydroxyl/hydroxyl gronp to an insoluble polymer. A necessary prerequisite is that anchoring groups (linkers) are introdnced into the polymeric material (step 1). The first protected monomer is then reacted with the functional gronp of the linker (step 2). The... 

In anthracycUnes, where the aglycone is fi-rhodomydnone = R ° = - OH) a glycoside chain can be attached either to carbon-7, or carbon-10 or both, such as in cosmomycin D (Struct. 4). 

Kelecom, a., B. Tursch, and M. Vanhaelen Chemical Studies of Marine Invertebrates XIX. Glycosidic Chain Structure of Thelothurins A and B, Two New Saponins from the Indo-Pacific Sea Cucumber Thelenota ananas Jaeger (Echinodermata). Bull. Soc. Chim. Belg. 85, 277 (1976). 

Crosslinking of glycosidic chains reduces swelling and loss of viscosity due to temperature, shear, and acid... 

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