Polysaccharide interaction between

Separation of enantiomers by physical or chemical methods requires the use of a chiral material, reagent, or catalyst. Both natural materials, such as polysaccharides and proteins, and solids that have been synthetically modified to incorporate chiral structures have been developed for use in separation of enantiomers by HPLC. The use of a chiral stationary phase makes the interactions between the two enantiomers with the adsorbent nonidentical and thus establishes a different rate of elution through the column. The interactions typically include hydrogen bonding, dipolar interactions, and n-n interactions. These attractive interactions may be disturbed by steric repulsions, and frequently the basis of enantioselectivity is a better steric fit for one of the two enantiomers. ... 

Polysaccharides can regulate weak interactions between protein molecules. A recent example is the effect of low molecular weight heparin molecules on the weak dimerisation of the plasminogen growth factor NKl, or at least a mutant thereof [135]. 

Laurent, T. C., The interaction between polysaccharides and other macromolecules. 5. The solubility of proteins in the presence of dextran, Biochem.., 89, 253, 1963. 

Attachment There is a high specificity in the interaction between virus and host. The most common basis for host specificity involves the attachment process. The virus particle itself has one or more proteins on the outside which interact with specific cell surface components called receptors. The receptors on the cell surface are normal surface components of the host, such as proteins, polysaccharides, or lipoprotein-polysaccharide complexes, to which the virus particle attaches. In the absence of the receptor site, the virus cannot adsorb, and hence cannot infect. If the receptor site is altered, the host may become resistant to virus infection. However, mutants of the virus can also arise which are able to adsorb to resistant hosts. 

Above we have shown the attractiveness of the so-called green nanocomposites, although the research on these materials can still be considered to be in an embryonic phase. It can be expected that diverse nano- or micro-particles of silica, silicates, LDHs and carbonates could be used as ecological and low cost nanofillers that can be assembled with polysaccharides and other biopolymers. The controlled modification of natural polymers can alter the nature of the interactions between components, affording new formulations that could lead to bioplastics with improved mechanical and barrier properties. 

As previously mentioned above, the chiral recognition abilities of the phenyl-carbamates of polysaccharides are greatly influenced by the substituents on the phenyl groups. In order to evaluate the effect of the substituents on the interaction between CSPs and solutes, the retention times of acetone and the first-eluted isomer of l-(9-anthryl)-2,2,2-trifluoroethanol (39) on 3- and 4-substituted CSPs are plotted against the Hammett parameter a of the substituents (Figure 3.33).130 The retention times of acetone tend to increase as the electron-withdrawing power of the substituents increases, whereas those of the first-eluted isomer of 39 tend to decrease. These results indicate that... 

Clearly, further studies will be necessary to sort out the multiple factors involved in the in vivo immune response to C. neoformans carbohydrate-mimetic peptides. Several conclusions may be drawn from the results to date. Peptides that mimic the cryptococcal capsular polysaccharide show specificity, in that each peptide binds with differing affinity to closely related mAbs [140,149]. The pattern of binding to protective and nonprotective mAbs differs between the mimetic peptides and the polysaccharide [140]. Protective efficacy is related to the location of carbohydrate epitopes recognized by these mAbs, within the polysaccharide capsule, but hkely also depends on interactions between mAbs and cellular responses [149]. Peptides have been shown to be functional, immunogenic mimics, but their protective efficacy depends on multiple factors, including the type of Abs elicited and interactions with the cellular immune system. Protective efficacy does not correlate with binding affinity to representative mAbs, but rather depends on the nature of these interactions. 

Big molecules of life include the proteins, nucleic acids, polysaccharides, and a few other more exotic constrncts of nature. Generally, it is the interactions between big molecules and small ones that nnderlie really interesting things taste or smeU or the beneficial actions of drugs, for example. 

Cell components or metabolites capable of recognizing individual and specific molecules can be used as the sensory elements in molecular sensors [11]. The sensors may be enzymes, sequences of nucleic acids (RNA or DNA), antibodies, polysaccharides, or other reporter molecules. Antibodies, specific for a microorganism used in the biotreatment, can be coupled to fluorochromes to increase sensitivity of detection. Such antibodies are useful in monitoring the fate of bacteria released into the environment for the treatment of a polluted site. Fluorescent or enzyme-linked immunoassays have been derived and can be used for a variety of contaminants, including pesticides and chlorinated polycyclic hydrocarbons. Enzymes specific for pollutants and attached to matrices detecting interactions between enzyme and pollutant are used in online biosensors of water and gas biotreatment [20,21]. 

A good example of this interaction in catalysis is the hydrolysis of the bacterial cell wall polysaccharide by lysozyme. This enzyme contains two carboxylic gronps at its active site and, in active enzyme one must be in dissociated—COO, the other in the undissociated—COOH form. Therefore, the pK s of the two carboxylic groups ate different. This difference in dissociation constant is a consequence of the neighbouring amino acid residues and of the interactions between the functional groups in the microenvironment. 

Figure 17.2 Schematic representation of the molecular weight distribution of unfractionated heparin (UH) and of low molecular weight heparin (LMWH). In the lower part of the figure, the polysaccharide chain of heparin, the pentasaccharide sequence, and the interaction between heparin, antithrombin (AT), thrombin, and factor Xa is represented. (Reproduced from Boneu B.Thrombosis Research 2000 100 V113-20, with permission from Elsevier Science.)...

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