Maltotriose-producing amylases

Naltotriose-producing Amylases. Amylases that produce maltotriose from starch as the major end-product have not been reported commonly. Indeed the only enzyme in this category is the enzyme from Streptomyces griseus (24). This is an exo-acting enzyme that hydrolyses its substrate from the non-reducing end to produce maltotriose in the a-configuration (31). The enzyme hydrolyses short chain amylose completely but the extent of hydrolysis with starch and waxy maize starch as substrate is 55 and 51% respectively. The optimum pH for activity is 5.6-6.0 and the enzyme is stable up to 40 C but rapidly denatured at temperatures above 45 C. 

Pullulan is hydrolyzed by pullulanase at the a-(l - 6) bonds, producing maltotriose plus some maltotetraose. Salivary alpha amylase cleaves at the maltotetraosyl units, when the a-(1 -> 4) linkage next to the a-(1 -> 6) bond and towards the reducing end of the maltotetraose unit is split (dotted arrow marked A in 108). The size of units released by alpha amylase, as judged... 

Fig. 9.—Radioautograph of paper chromatogram showing radioactive Schardinger dextrins produced from radioactive glycogen by B. macerans amylase. Small amounts of linear oligosaccharides together with unreacted residues from the glycogen were removed by beta amylase action and converted to maltose and maltotriose.

Starch degradation in dicot seeds yields more glucose and maltotriose than that in cereals, where more maltose is produced. This is related, in part, to the relative activity of jS-amylase in the two classes of seeds. 

To produce ethanol from starchy materials, such as cereal grains, the starch must first be converted into fermentable sugars, which are formed by starch degradation by amylases and maltases (see Section 4.5.6.1.3). For the production of beer, for example, yeast strains are selected that metabolise maltose and maltotriose (which... 

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