Biological macromolecules polysaccharides

Polymeric carbohydrates are usually encountered as distributions, so high resolution is rarely important. Of all biological macromolecules, carbohydrates are particularly amenable to analysis by GPC because hydrophobic interactions are typically weak. A section below is devoted to the analyses of carboxymethylcellulose and xanthan. Other examples of polysaccharides of interest are hyaluronic acid,62 polymers of (l-glucose,121125 heparin,126127 cellulose and chitin,128 and Mucorales extracellular polysaccharides.129... 

Macromolecules such as proteins, polysaccharides, nucleic acids differ only in their physicochemical properties within the individual groups and their isolation on the basis of these differences is therefore difficult and time consuming. Considerable decreases may occur during their isolation procedure due to denaturation, cleavage, enz3rmatic hydrolysis, etc. The ability to bind other molecules reversibly is one of the most important properties of these molecules. The formation of specific and reversible complexes of biological macromolecules can serve as basis of their separation, purification and analysis by the affinity chromatography [6]. 

A large number of macromolecules possess a pronounced amphiphilicity in every repeat unit. Typical examples are synthetic polymers like poly(l-vinylimidazole), poly(JV-isopropylacrylamide), poly(2-ethyl acrylic acid), poly(styrene sulfonate), poly(4-vinylpyridine), methylcellulose, etc. Some of them are shown in Fig. 23. In each repeat unit of such polymers there are hydrophilic (polar) and hydrophobic (nonpolar) atomic groups, which have different affinity to water or other polar solvents. Also, many of the important biopolymers (proteins, polysaccharides, phospholipids) are typical amphiphiles. Moreover, among the synthetic polymers, polyamphiphiles are very close to biological macromolecules in nature and behavior. In principle, they may provide useful analogs of proteins and are important for modeling some fundamental properties and sophisticated functions of biopolymers such as protein folding and enzymatic activity. 

Owing to the innate complexity of proteins, nucleic acids, and polysaccharides, a proper understanding of biological macromolecules requires a diverse array of experimental and theoretical techniques. As a result, a number of important databases containing the diverse array of information, either experimental or computational, are deposited into a number of databases, which are free and publicly available to the global community. 

The field of application of this method is quite large, especially at the level of all classes of biological macromolecules, e.g., polysaccharides, antibiotics, natural metal complexes, etc. This is shown by the observation of ions with masses of 4000 units produced by peptides composed of 29 amino acid residues [84]. The method seems to be sensitive in the ng and pg range of sample detection. 

Biological macromolecules such as polysaccharides, fibrous or membrane proteins characteristically adopt a unique secondary structure which may be related to a variety of physical or biological properties. Elucidation of the three-dimensional structure of these systems is not always straightforward, because, in many instances, they are insoluble in ordinary solvent systems, and crystallization for X-ray diffraction study is extremely difficult. A possible disruption of a particular secondary structure should also be anticipated, when they are solublized in a solvent or detergent. Therefore it is essential to clarify their secondary structures either in the solid, gel or membrane-bound state without any attempt at solubilization. 

We demonstrate here how the NMR approach is a very useful means to reveal the conformation and dynamics of biological macromolecule with reference to the conformation-dependent displacements of peaks, with illustrative examples from polysaccharides, structural and membrane proteins and biologically active peptides. It is emphasized here that careful examination of the displacements of or N chemical shifts can serve as an excellent probe when referred to an accumulated data base of reference samples of known secondary structure. 

The three most abundant biological macromolecules— proteins, nucleic acids, and polysaccharides—are all polymers composed of multiple covalently linked identical or nearly identical small molecules, or monomers (Figure 2-11). The covalent bonds between monomer molecules usually are formed by dehydration reactions in which a water molecule is lost ... 

Edible films and coatings are thin materials made from biological macromolecules (biopolymers).1 The main biopolymers used in preparing biofilms are polysaccharides2 and proteins.3,4 Among the most studied polysaccharides are pectin, cellulose and derivatives, alginates, carrageenan, chitosan and starch.1 5... 

Recently, our research attempted to find new materials based on blends of biological macromolecules, such as structural proteins and polysaccharides, and hydrophilic synthetic polymers, such as poly(vinyl alcohol) (PVA), in which the biocompatibility of the former is combined to the mechanical properties of the latter ((. ... 

The trans-cyclic rings of such polysaccharide derivatives are of interest in that they are very susceptible to nucleophiles, "" and sulfhydryl groups may react similarly to amino groups at near-neutral pH. "" In the case of the water-insoluble cellulose trflns-2,3-carbonate, the reaction has been applied to the insolubilization of biological macromolecules. 

H ACTIVE FIGURE 1.B Informational macromolecules. Biological macromolecules are informational. The sequence of monomeric units in a biological polymer has the potential to contain information if the order of units is not overly repetitive. Nucleic acids and proteins are informational macromolecules polysaccharides are not. Sign in atwww.thomsonedu.com/login to explore an interactive version of this figure. 

Most polymer carriers per se do not possess the ability to recognize the target site. Consequently, biological macromolecules such as polysaccharides, antibodies, and toxin fragments are introduced into the polymer carrier as the directional component and to ensure the required selectivity. The functional groups of the polymer are usually modified or activated to effect coupling of the biomolecule (Table 5.9). 

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