Carbohydrates specific types

Protein fractions having lectin activity have been extracted from mitochondria, plasma, and Golgi membranes, and from the endoplasmic reticulum of mung-bean hypocotyls, as well as from total-membrane fractions from a variety of plant tissues.257 The carbohydrate specificity of the lectin fractions differs with the membrane type. It is conceivable that, in addition to cell-wall lectin-membrane interactions, there may also be membrane lectin-cell wall, noncovalent bonds. 

The polysaccharides which will be considered in this paper are all found in the extracellular capsular material which surrounds the cell wall of bacteria belonging to the Genus Klebsiella. The carbohydrate nature of these capsules was first demonstrated in 1914 by Toenniessen (J ) and in 1926 Julianelle (2) was the first person to report on the presence of sharply defined and high specific types of polysaccharides in the different serotypes. 

Fukuda M (1994) Cell surface carbohydrates cell type specific expression In Fukuda M, Hindsgaul O (eds) Frontiers in Molecular Biology, Molecular Glycobiology. IRL Press, Oxford, p 1... 

Antibodies directed against recombinant erythropoietin have been obtained from rabbits immunized with the hormone and Freunds complete adjuvant [64], Two sets of antibodies are present in the serum of rabbits that have been immunized, Fig. (3C). The results of oxidation of the erythropoietin with periodate, Fig. (25A), reaction of the antibodies with lectins of known carbohydrate specificity, Fig. (25B) and inhibition of the antibodies with the structural monosaccharide residues of the hormone, Fig. (26), have established the types of antibodies to be anti-carbohydrate antibodies and the immunodeterminants for these antibodies are oligosaccharides with the following structure N-acetyl neuraminyl a(2->3)... 

Carbohydrate nutrition is different in nature from the nutrition of amino acids, fats, vitamins, and minerals. Humans have no dietary requirement for any specific type of carbohydrate. All carbohydrates of the body can be synthesized from dietary glucose or fructose, the major sugars in the diet. The body stores sugar in the form of glycogen, a polysaccharide composed of glucose units. 

Virtually all bacterial species and genera express lectins or lectin-like activities, frequently of more than one type and with different specificities. However, it is usually not known whether individual cells coexpress multiple types of lectin or each lectin is confined to a distinct cell population. Many Gram negative bacteria (for example, Escherichia coli and Salmonellae spp.) and a few Gram positive ones (e.g. certain actinomyces), produce surface lectins that are often in the form of submicroscopic hairlike appendages known as fimbriae (pili) that protrude from the surface of the cells. The best characterized bacterial surface lectins with respect to their molecular properties, carbohydrate specificity and genetics are the type 1 fimbriae specific for mannose and the type P fimbriae specific for galabiose, [Gal(al-4)Gal], produced by many strains of E. coli. Other examples are S fimbriae of E. coli, specific for NeuAc(a2-3)Gal, and type 2... 

Although very similar in their carbohydrate specificity, the lectins from E. coli and K. pneumoniae differ in their affinity for aromatic mannosides. Thus, 4-methylumbelli-feryl a-mannoside is about 10-fold more effective than p-nitrophenyl a-mannoside in inhibiting yeast aggregation by type 1 fimbriated E. coli, while it is only 4 times more effective than p-nitrophenyl a-mannoside as inhibitor of K. pneumoniae [50]. Since the FimH subunits of the two organisms exhibit 88% homology, the possibility has been... 

Pertussis toxin, produced by virulent strains of B. pertussis, the etiological agent of whooping cough, is a classical A-B type toxin comprised of an A subunit that possesses ADP-ribosyltransferase activity and is responsible for most of the biological effects of the toxin, and a B subunit with affinity for carbohydrates. The B subunit of the pertussis toxin is a pentamer composed of four different subunits (S2-S5). The toxin acts as a hemagglutinin and exhibits dual carbohydrate specificity, due to... 

M. Fukuda, Cell surface carbohydrates cell-type specific expression, in M. Fukuda and O. Hindsgaul (Eds.), Molecular Glycobiology, Oxford University Press, Oxford, 1994, pp. 1-52. 

We already know from our earlier mapping of the path of carbon in photosynthesis that we need not only a reducing agent for the reduction of carbohydrate but also, in addition, a rather specific type of chemical. Since we know the exact steps for carbon reduction, we were able to... 

Clinicians are often inclined to implicate specific dietary habits in the onset of diabetes. However, it appears that none of the ordinary foodstuffs—carbohydrates, proteins, and lipids— has such a specific effect, and overindulgence per se facilitates the onset of diabetes. The total caloric intake is more important in triggering diabetes than any specific type of food. 

Gangliosides. Considerable information on the incorporation in vivo of various carbohydrate precursors into gangliosides has recently become available (Rad in et al., 1957, Moser and Karnovsky, 1959, Burton et al., 1963, and Suzuki and Korey, 1963). These studies have not produced evidence for a specific type of pathway. Burton et al. (1959) and Burton (1960) have discussed possible routes of biosynthesis. The possible routes are diagrammatically presented as follows ... 

The proton-decoupled C-NMR spectrum of carbohydrates gives a signal for each of the specific types of carbons present. For highly asymmetric carbohydrate units, this usually means a signal for each of the carbons in the asynmietric unit. This has been demonstrated for a number of saccharides, such as amylose [40], cyclomaltodextrins [41], dextrans [42], and many others [18]. It is most clearly demonstrated for sucrose in which 12 distinct signals are produced, one for each of the 12 carbons (see Fig. 12.4A). 

Molecular mechanics is broken down into several parts in this Encyclopedia. The qualitative aspects of the subject predate computational chemistry, and are to be found in Conformational Analysis 1 Conformational Analysis 2 and Conformational Analysis 3. A brief introduction to molecular mechanics itself is given in Force Fields A Brief Introduction. Molecular dynamics is discussed in many articles, including Molecular Dynamics Techniques and Applications to Proteins. Much of the remainder of molecular mechanics is concerned with, force fields and is summarized in Force Fields A General Discussion, or under the specific type of compound involved, e.g., carbohydrates (see Carbohydrate Force Fields) or nucleic acids (see Nucleic Acid Force Fields). 

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