Pullulan-degrading enzymes

Table L Action of Pullulan Degrading Enzymes on Pullulan and Starch...

M. Domafi-Pytka, and J. Bardowski, Pullulan degrading enzymes of bacterial origin, Crit. Rev. Microbiol, 30 (2), 107-121,2004. 

Isoamylase (EC 3.2.1.68) is a starch degrading enzyme which hydrolyzes all the (1- )-linkages in amylopectin and glycogen, but which has very little or no action on pullulan. 

The plant and bacterial enzymes capable of hydrolyzing pullulan do not have identical specificities. In particular, the plant enzymes have little or no action on glycogen and phytoglycogen under conditions in which they readily hydrolyze amylopectin and its /3-dextrin. To stress this difference (the bacterial enzymes are capable of degrading both glycogen and phytoglycogen), Manners (1997) recommended different nomenclature for bacterial enzymes, to be called pullulanase, and the plant enzymes, to be called limit dextrinases. 

Information on the hydrolytic activity in marine sediments has been obtained from the use of model substrates labeled with fluorescent dyes such as methylumbelliferone (MUF) or fluorescein. These substrates may be small dimeric molecules, the hydrolytic cleavage of which releases the fluorescence signal, which is then indicative of the activity of specific enzymes such as glucosidase, chitobiase, lipase, ami-nopeptidase or esterase (Chrost 1991). Also large fluorescently labeled polymers such as the polysaccharides laminarin or pullulan have been used in experiments to demonstrate the mechanism and kinetics of bacterial degradation (Amosti 1996). 

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