Depolymerization, enzymic, isolation

Enzymes are specific, however. For example, starch is depolymerized using enzymes to D-glucose (dextrose). The solution of glucose is then treated with glucose isomerase [9055-00-9] to give D-fmctose in about 42% yield. No D-mannose is formed. Addition of isolated D-fmctose to this solution gives the common 55% high fmctose com symp (HFCS) so widely used in soft drinks in the United States. HFCS is about 1.5 times as sweet as sucrose. 

Saprophytic anaerobic bacteria, e.g. the ruminant bacterium Lachnospira multiparus and the methane digestor isolate, Clostridium populeti, secrete only acidic pectate lyases that exhibit an exolytic/endolytic depolymerization toward polygalacturonate. It will be important to determine if this acidic property contributes to the adsorption of these enzymes to the secreting bacterium, perhaps contributing to the efficiency with which the bacteria are able to assimilate the products generated by these enzymes. 

Some microorganisms degrading condensed tannins have been isolated and described, but no reports on the mechanism of the depolymerization process, or the enzymes involved in biodegradation, have appeared. It must be stressed that condensed tannin degradation may be associated with other... 

Brown The determinations of size of the cell-wall capillaries and the cellulases of fungi indicate that the enzymes that have been isolated to date are so large that they probably can penetrate only a few cell-wall capillaries in wood and cotton. This conclusion is supported by Cowling s DP data for the action of the white-rot fungus, Polyporus versicolor, on wood (Figure 13). But it is also contradicted by the same type of data for the effect of both the brown-rot fungus, Poria monticola, on wood (Figure 13) and of Myrothecium verrucaria on mercerized cotton as shown by Selby (60). Thus we believe that the catalysts responsible for the initial depolymerization of cellulose in wood and cotton by these two... 

In 1977, Tokiwa and Suzuki reported that some lipases, which are extracellular enzymes that usually cleave esters in oils and fats, are also able to attack ester bonds in some aliphatic polyesters and can depolymerize such materials [38]. Aliphatic polyesters, however, exhibit only limited useful properties for many applications. Aromatic polyesters, such as PET and PBT, which are widely applied because of their excellent properties, are not attacked by hydrolytic enzymes. This led to the development of aliphatic-aromatic polyesters as biodegradable plastics that present a compromise between biodegradability and material properties [39]. Recently, however, Muller et al. [40] have isolated a hydrolase (TfH) from Thermofibida fusca which is able to depolymerize the aromatic polyester PET at a high rate in contrast to other hydrolases such as lipases. They have demonstrated for the first time that commercial PET can be effectively hydrolyzed by an enzyme at a rate that does not exclude a biological recycling of PET. The effective depolymerization of PET with the enzyme TfH will result in water... 

Purdy RE, Kolattukudy PE (1973) Depolymerization of a hydroxy fatty-acid biopolymer, cutin, by an extracellular enzyme fl om Fusarium solani pisi—isolation and some properties of the enzyme. Arch Biochem Biophys 159 61-69... 

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