Pullulanase specificity

In comparison with a pullulanase, the purified amylopullulanase displayed 3-fold higher specificity towards soluble starch and amylopectin and 7-fold higher specificity towards glycogen (12). The amylopullulanase hydrolyzed various high molecular weight starch substrates (Table II). Even the mammalian glycogen which... 

The major enzymes that have been used for studying structures of starch polymers and fragments from them are the endo-acting a-amylases, the exo-acting glucoamylase and (3-amylases, and the debranching enzymes, isoamylases and pullulanases. These enzymes have varied and diverse specificities that have been extensively studied (see previous sections). 

Starch is first liquefied and hydrolyzed to specific dextrose equivalents with hydrochloric acid. After evaporation to 60 percent solids, a saccharifying enzyme (fungal a-amylase) is added to continue hydrolysis to the desired level. By choosing two or more types of enzymes (such as a-amylase, -amylase, glu-coamylase, pullulanase) and adjusting the initial acid hydrolysis, syrups with different ratios of dextrose, maltose, and higher saccharides can be obtained.92... 

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. 

Data on the fine structure of amylopectin from several sources have been obtained through the action of )8-amylase and pullulanase 104, 105, 106). Pullulanase removes specifically the a-D-(l- 6) linkages in amylo-... 

Eurther conversion (saccharification) to dextrose can be done using glucoamylase. Starch consists of polymeric linear a-1,4 linked dextrose units (amylose, 25 % of the starch) and polymeric mixed a-l,4/a-l,6 linked dextrose units (amylopectin, 75 % of the starch). Eor enzymatic degradation besides a-1,4 specific amylases also a-1,6 specific amylases (pullulanases) are required. A portion of the dextrose can be converted into fructose with a glucose isomerase yielding a high fructose com symp (MFCS). 

Pullulanase type I hydrolyzes a-1,6 linkages in amylopectin, pullulan or limit dextrins with high specificity. Pullulan is completely degraded in a random fashion... 

That these two heptasaccharides were not produced in equal amounts, as migiit be expected on a purely statistical basis, is consistent with the known specificity of pullulanase."... 

According to substrate specificity and different decomposition of products, pullulanase can be broadly divided into four categories ... 

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