Polysaccharide depolymerase

This principle has been utilized to assess intrinsic subsite binding energies for enzymes that have substrate binding subsites and exosites topologically distant from the reactive site (e.g., polysaccharide depolymerases and pro-teinases). 

The macroscopic velocity is the sum of all microscopic velocities of an enzyme system which acts on a polymer at several different positions, thus yielding a number of different products from the same substrate. One good example is polysaccharide depolymerase ... 

The properties and action patterns of glycosidases and polysaccharide depolymerases have been reviewed,2 5 as also have the enzymes involved in biosynthetic pathways.6,7 An understanding of biosynthesis can provide insights into the structures of polysaccharides. Reviews concerning particular polysaccharides have appeared, and references to these will be given in relevant sections. 

Application of Polysaccharide Depolymerases to Manufacture Bioactive Oiigosaccharides... 

Sutherland, I. W. (1972). The exopolysaccharides of Klebsiella serotype 2 strains as substrates for phage-induced polysaccharide depolymerases. J Gen Microbiol, 70(2), 331-8. 

Each fruit has specific quantities and ratio of pectin, hemicelluloses and cellulose. These polysaccharides are important concerning enzymes activities required to produce juices and concentrates. Moreover, even if molecular weight and methylation degree of the pectin are specific for each fruit, during the fruit maturation, endogenous pectinases depolymerases and esterase are changing the pectin characteristics This broad variability of raw material makes difficult the standardisation of fruits processing. 

The way in which a polysaccharide is released from the isoprenoid lipid is not yet known. Most probably, enzymes are present that cleave the terminal, phosphate-linked, monosaccharide residue. The chain length of a polysaccharide may depend on the growth rate that is, a higher growth-rate might lead to a faster turnover of the carrier lipid and release of polysaccharide of lower molecular weight. Instances are known where variable chain-length results from the action of depolymerases.239... 

Type III. D-Glucopyranosyl residues are transferred from uridine 5-(a-D-glucopyranosyl pyrophosphate) and D-glucosyluronic acid residues from uridine 5-(D-glucopyranosyluronic acid pyrophosphate) in a 1 1 ratio. The resulting polysaccharide was identified by precipitation with a specific antiserum, followed by hydrolysis with acid or with a depolymerase known to hydrolyze Type III polysaccharides only. The results of immuno-electrophoretic analysis showed that the enzymically synthesized polymer has a molecular weight of the same order of magnitude as that of the polysaccharide produced in vivo. ... 

Since the enzyme as routinely prepared is contaminated with a small amount of polysaccharide, the addition of a glycosyl acceptor to the reaction mixture is not usually required. Acceptor must, however, be added, after the enzyme has been exhaustively treated with Type III depolymerase (which removes the adhering polysaccharide). It has been found that the smallest oligosaccharides which would act as acceptors consist of 8 to 12 repeating disaccharide residues. ... 

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]. 

Pelkonen S, Aalto J, Finne J (1992) Differential activities of bacteriophage depolymerase on bacterial polysaccharide binding is essential but degradation is inhibitory in phage infection of K1-defective Escherichia coli. J Bacteriol 174 7757-7761... 

A depolymerase active towards Klebsiella type 11 capsular polysaccharide was induced by the action of bacteriophage II on a Klebsiella species. The enzyme catalysed the hydrolyses of j8-D-glucopyranuronosyl-(l -> 3)-D-glucuronic... 

Several kinds of extracellular depolymerases have been purified and characterised from various microorganisms [187, 189,191, 195-197], All the depolymerases are comprised of an N-terminal catalytic domain, a C-terminal substrate binding domain, and a linker region connecting the two domains. Similar catalytic and binding domains have also been identified in other depolymerising enzymes that hydrolyse water-insoluble polysaccharides such as cellulose [198], xylan [198,199], and chitin [200], The catalytic domain contains a lipase box pentapeptide [Gly-Xi-Ser-X2-Gly] as the active site, which is common for serine hydrolase [201]. Further detailed aspects on the structure and mechanisms of PHA depolymerase (EC 3.1.1.76) can be found elsewhere [202]. 

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