Polysaccharides enzymatic activity

Y. Kakizawa, K. Akiyoshi, K. Nakamura, and J. Sunamoto, in Enzymatic Activity of Lipase Complexed with Nanoparticle of Hydrophobized Polysaccharide, Kyoto, Japan, 1998, p. III-806. Society of Polymer Science, Japan (Spsj). 

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. 

Because the influence of drying parameters is not the same for all materials, optimal drying conditions vary depending on the final objective volatile retention, preservation of enzymatic activity and avoidance of protein denaturation, fat oxidation or crystallisation. Furthermore, some interactive influences may appear between components, an effect that is positive for protection of labile compounds by a network of polymers as polysaccharides, gums, proteins (Dumoulin and Bimbenet 1998). The phenomena may vary between centre and surface of drops, with some possible segregation by internal movement in the drop. 

Within the extracts (thermal or enzymatic), besides polysaccharides, mannoproteins were proven to be the main components, the molecular characterization of which has been carried out using SEC and SDS-PAGE (Martfnez-Rodrfguez et al. 2007 Nunez et al. 2006). Results showed in both cell wall extracts a protein band corresponding to a relative molecular mass of 30kDa (Eig. 5.9). Moreover, three bands, which were absent from the extract obtained enzymatically, with relative molecular masses between lOkDa and 21.5 kDa were observed in the thermal extract. Only glycoproteins with Mr between 10 kDa and 21.5 kDa, were proven to be foam-active though the protein at 30 kDa (also present in the enzymatic extract) was found to be inactive. 

Enzymes acting on molecules like cellulose, which are insoluble and of similar, or even greater size than themselves, obviously require delicate tertiary structures comparison of the sequence of approximately 50 fungal and bacterial cellulase genes and of some other polysaccharide hydrolase (for review see [8]) has offered evidence that such proteins are composed of separate domains, which allow a spacial separation of the sites involved in substrate recognition and enzymatic activity. 

In spite of the enormous complexity, the study of the effect of various solutes on the solvation of biomolecules such as proteins, nucleic acids, glycoproteins, polysaccharides, etc., is important. The knowledge of such solute effects can give us a method of controlling biochemical processes such as enzymatic activity, binding of proteins to DNA, etc. No doubt, nature uses these same methods to control and regulate its own processes. 

All tailed phages have evolved tailspike and fiber proteins for efficient virus-host-interactions. These specialized adhesions mediate the recognition and attachment to the bacterial surface and constitute the key determinants for host specificity. Interestingly, many spikes and fibers are composed of homotrimeric complexes which remain stable even in the presence of sodium dodecyl sulfate (SDS) [12, 14, 30-34], Several phages have developed tailspike proteins with an enzymatic activity in order to penetrate the thick layer of lipopolysaccharides or capsular polysaccharides of many pathogenic bacteria. These capsule-specific depolymerases (hydrolases or lyases) are required to gain access to and to fix the phage at the bacterial outer membrane [13, 14, 35-38]. 

Measurements of excimer or exciplex fluorescence can be used to determine whether a pair of macromolecules or two regions of a macromolecule are able to come in close contact during the lifetime of the excited state. Derivatives of pyrene that can be attached to various functional groups in proteins, lipids or polysaccharides lend themselves well to such studies [57-61]. In one application, the A-terminus of the EcoRl restriction endonuclease was labeled with N-(l-pyrenyl)iodoacetamide [62]. A broad excimer emission band at 480 nm indicated that the A-termini of two molecules come into close proximity when the protein dimerizes. The A-termini are essential for enzymatic activity but are too disordered to be seen in a crystal structure of the protein. 

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