Hybrid carbohydrate

FIGURE 9.26 The carbohydrate tnoiedes of glycoproteins may be linked to the protein via (a) serine or threonine residues (in the O-linked saccharides) or (b) asparagine residues (in the N-linked saccharides), (c) N-Linked glycoproteins are of three types high mannose, complex, and hybrid, the latter of which combines structures found in the high mannose and complex saccharides. 

Synthetic aspects for access to monovalent fullerene-carbohydrate hybrids were highlighted, but only a few biological applications were mentioned. In contrast, multivalent presentation of saccharides by multiple anchorages to the same structure, or their presentation as antennary glycodendrons, has generated promising results. 

Biotin-hydrazide has been used to biotinylate antibodies at their oxidized carbohydrate residues (O Shanessy et al., 1984, 1987 O Shanessy and Quarles, 1985 Hoffman and O Shannessy, 1988), to modify the low-density lipoprotein (LDL) receptor (Wade et al., 1985), to biotinylate nerve growth factor (NGF) (Rosenberg et al., 1986), and to modify cytosine groups in oligonucleotides to produce probes suitable for hybridization assays (Reisfeld et al., 1987) (Chapter 27, Section 2.3). 

Most eukaryotic mRNA molecules have up to 250 adenine bases at their 3 end. These poly (A) tails can be used in the affinity chromatographic purification of mRNA from a total cellular RNA extract. Under high salt conditions, poly (A) will hybridize to oligo-dT-cellulose or poly(U)-sepharose. These materials are polymers of 10 to 20 deoxythymidine or uridine nucleotides covalently bound to a carbohydrate support. They bind mRNA containing poly (A) tails as short as 20 residues. rRNA and tRNA do not possess poly (A) sequences and will not bind. After washing the mRNA can be eluted with a low salt buffer. 

In the first part of this chapter we will describe some general aspects of hydrothermal carbonization, using either carbohydrates or complex biomass to control structure formation in the presence of various catalysts and/or templates. In the second part, we then describe some of the most promising applications of these car-bon/hybrid materials in energy applications. 

The hydrothermal carbons obtained in the end from soluble, non-structural carbohydrates are micrometer sized, spherically shaped particle dispersions, containing a sp2 hybridized backbone (also responsible for the brown to black color) decorated with a dense layer of polar oxygenated functionalities still remaining from the original carbohydrate. The presence of these surface groups offers the possibility of further functionalization and makes the materials more hydrophilic and well-dispersible in water. The size of the final particles depends mainly on the carbonization time and precursor concentration inside the autoclave, as well as additives and stabilizers potentially added to the primary reaction recipe. An SEM image of a model reaction illustrating this dispersion state is shown in Fig. 7.1. 

This report was the first of its type to show the ability of such a large covalently linked carbohydrate (neomycin) to aid in RNA-DNA hybrid complex-ation. N-Neo-conjugate and a 7-base-long RNA sequence present in a-sarcin loop can form a stable hybrid duplex. The stability of a hybrid duplex with addition of one neomycin equivalent is comparable to the stability of a hybrid duplex where the DNA has a covalent bond to neomycin. The presence of a single mismatch decreases the melting temperature of both neomycin-conjugated... 

Enolates represent a special class of sp -hybridized C(l) nucleophiles. This is an important and developing aspect of carbohydrate reactivity and the carbonyl function can either be located at C(2), or be external to the sugar ring (as in sialic acid derivatives). Although the latter are not strictly C(l) nucleophiles, both their value in C-glycoside synthesis and relationship to other topics covered in this chapter merit inclusion of these systems. 

Lawal, O. S. (2004). Succinyl and acetyl starch derivatives of a hybrid maize physicochemical characteristics and retrogradation properties monitored by differential scanning calorimetry. Carbohydr. Res., 339,2673-2682. 

We use sugar amino add as a fundional, sucdnct classification term, although a plethora of terms have been proposed in the literature for compounds derived from Saa. These include saccharide-peptide hybrids, glycosamino adds, peptidosaccharides, sac-charopeptides, amide-linked carbohydrates, and carbopeptoids, although the latter compounds most often do not have a peptoid functionality. In some cases Saa are linked to each other, in other cases to amino acids. 

Other known oligonucleotide analogs include oligomers in which the heterocyclic bases have been modified [155] or replaced by other types of compound [156], Solid-phase syntheses of hybrids of DNA with peptides [157-163], with carbohydrates [164,165], and with PNA (peptide nucleic acids, see Section 16.4.1.2 [166-168]) have also been reported, and several strategies have been developed that enable the preparation of oligonucleotides with a modified 5 - or 3 -terminus [169-174] or of cyclic oligonucleotides [122,175], Various techniques for the parallel solid-phase synthesis of oligonucleotides have been developed for the preparation of compound libraries [176-181],... 

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