Starch hydrolysis pullulanase

Pullulanase (cf. 4.4.5.1.4) is utilized in the brewing process and in starch hydrolysis. In combination with P-amylase, it is possible to produce a starch sirup with a high maltose content. 

Roy, I. and Gupta, M.N., Hydrolysis of starch by a mixture of glucoamylase and pullulanase entrapped individually in calcium alginate beads, Enzyme Microbial Tech., 34 (2004) 26-32. 

There have been several examinations of the structure of Nageli dextrin,405407 which is prepared by the prolonged action of acid on granular starch. In one study,405 there was separated from waxy maize a branched fraction that was resistant to pullulanase action. As this fraction contained some molecules having two branch points that were in close proximity, it was considered that this may have hindered hydrolysis, and that it could be of relevance to studies on the structure of the original amylopectin. 

Although all amylose molecules were once considered to be linear, many amylose molecules cannot be completely hydrolyzed by (3-amylase. With a concurrent or mixed action of pullulanase and beta-amylase, however, amylose can be completely hydrolyzed to maltose.150,151 These results rule out the theory that the incomplete hydrolysis of amylose by (3-amylase is a result of retrogradation, i.e. junction zone formation. It is now clear that the incomplete hydrolysis of an amylose preparation by (3-amylase is due to branching of some molecules. The (3-amylolysis limit of amylose varies from 72% to 95%152,153 compared with 55-61% for amylopectin. Amylose of most cereal starches, such as maize,154 rice,155,156 wheat157 and barley,158 give >80% (3-amylolysis... 

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... 

Pullulanase Enzyme degrading pnUnlan, a branched starch pullulanase catalyzes the hydrolysis of the a-l,6-glncosidic linkage in a-glucans. Pullulanase preferentially hydrolyzes pnUnlan while isoamylase has a preference for glycogen and amylopectin. See WaUenfels, K Bender, H and Rached, J.R., Pnllnlanase from Aerobacter aerogenes production in a cell-bound state. Pnrification and properties of the enzymes, Biochem. Biophys. Res. 

B. cereus var. Mycoides could produce two kinds of starch enzymes /3-amylase and pullulanase, where the optimum condition pH is 6-6.5, temperature is 50°C, and the maximum conversion rate (maltose from starch by hydrolysis) is about 95% [18]. In the 1980s, Novo Nordisk Denmark had received Acidophilic Bacillus that hydrolyzed puUulan the pullulanase from it is now the most widely used, and has the largest output [18]. In 1986, Yoshiyuki Takasaki isolated B. subtilis producing heat and acid stable pullulanase, which could produce the mixture of pullulanase and amylase, of which the optimum pH of pullulanase was 7.0-7.5, but also maintained 50% of enzyme activity at pH 5.0 [19]. In 1987, E. Madi and G. Antranikian reported a simultaneous production of u-amylase, pullulanase and glucoamylase bacteria Clostridium thermosulfurgenes. In addition, some actinomycetes such as Streptomyces diastatochromogenes, Beauveria actinomycetes and Micromonosporaceae, Actinomycetes thermomonosporaceae also produce pullulanase. In plants, such as rice, beans, potatoes, sweet corn and malt, pullulanase was observed [20]. 

Figure 1 Expanded chromatograms from Dionex ion chromatograph of enzyme hydrolysates of corn and potato starch, the use of a single enzyme, amyloglucosidase (AMG), and a mixture of AMG, a-amylase (a-A), and pullulanase (PU), to show the effect on hydrolysis of limit dextrin. Anion exchange column AS6, with pulsed amperometric detection. Gradient flow solvents (1) ISOmmolT NaOH and (2) ISOmmoll NaOH + 500mmol I NaOOCCHs. Postcolumn addition of 0.3mmoll NaOH.

In the process a starch suspension containing the heat-stable a-amylase is heated briefly to 140 °C so that it forms a gel. This is sufficiently hydrolysed before the a-amylase is destroyed to allow it to be pumped to a vessel where more a-amylase is added, and the hydrolysis continues for about 30 min at 100 °C. At the end of this period about 10% of the a-1,4 links in the starch are hydrolysed and the gel is thin enough to be cooled to 55 °C without setting solid. Amyloglucosidase and pullulanase are stable at this lower temperature, and enough of these two enzymes are added to catalyse the hydrolysis of the starch to glucose over a two- or three-day period. Only some 2 or 3% of the links between the glucose units remain, and this, in fact, represents the equilibrium position of the hydrolysis. 

Malto-oligosacchaiides 0.3-0.6 a) Hydrolysis of the 1,6-a-glycosidic bonds in starch (debranching) by pullulanase b) controlled hydrolysis by a-amylase... 

Special products similar to maltose syrups are maltooligosaccharides containing 2-7 glucose units linked to each other by a-D-(1 4) bonds. They are obtained by enzymatic hydrolysis of starch with isoamylase or pullulanase and by hydrolysis of the obtained products using a-amylase. Maltooligosaccharides are fully utihsable sugars, which are used similarly to maltose syrups. 

Intracellular and extracellular pullulanases accelerated the hydrolysis of waxy corn starch by the glucoamylase of a Rhizopus species, but they are less active towards non-waxy corn starch. ... 

A. behaves like starch or amylose in reactions such as ->hydrolysis, derivatization or physical treatment (modified starches). Application of debranching - enzymes (pullulanase and iso-amylase) opens the possibility of total splitting of the a-1,6-linkages, thus enhancing hydrolysis as well as producing short-chain amyloses fit>m a. on a commercial scale. 

---