Action of Taka-amylase

PRODUCTS OF THE ENZYMIC DEGRADATION OF STARCH AND GLYCOGEN 295 4. Action of Taka-amylase ... 

A large amount of amylase inhibitors, of at least four kinds, were produced by Streptomyces sp. No. 280 when cultivated on 3% oatmeal medium and it was found that the molecular weight of the inhibitors were transformed to small molecules during the cultivation time. The transformation of the amylase inhibitor was found to result from degradation of its carbohydrate moiety by a-amylase in the culture broth. The amylase inhibitor was hydrolysed partially by the action of Taka-amylase A or hog pancreatic a-amylase. With hydrolysa-tion of amylase inhibitor by a-amylase, neutral sugars (mainly maltose) were... 

The action of Taka-amylase A, an a-amylase from Aspergillus oryzae, has been studied quantitatively by a product analysis method using unlabelled maltotriose and maltotriose labelled at the reducing end as substrates. ... 

These oligosaccharides were analyzed by h.p.l.c. It must be noted that the main products by the actions of salivary, hog pancreas and bacterial saccharifying a-amylase appear to be identical to each other. It was characterized as 4-0 -a-nigerosyl-D-glucose. The mode of action with Taka amylase seems to differ from those with salivary and pancreas amylases. 

Figure 9. Possible action pattern of Taka amylase, and release of tetra- and hep-tasaccharide ( ), site cleaved by Taka amylase (O), a-D-glucopyranosyl unit (-----------), (1 - 4)-D-glucosidic linkage (f), (1- 3)-D-glucosidic linkage.

Studies of the hydrolyses of cyclohexa-, cyclohepta-, and cyclo-octa-amyloses by Taka-amylase A (one of the a-amylases from Aspergillus oryzae) indicated that each cycloamylose binds to the same active site of the enzyme. Since there is little difference in the respective AG, Af/, and AS values for enzymic hydrolysis of these cycloamyloses, their binding modes appear to be similar. The extent of multiple attack on the cycloamyloses was not affected by temperature. A 4-phenylazobenzoyl derivative of Taka-amylase A has been used to investigate the active site of the enzyme. A. oryzae a-amylase has a synergistic effect on the action of the glucoamylase from A. awamori var. kawachi ... 

When acted upon by large amounts of amylases, the limit dextrins mentioned above are hydrolyzed further. Taka-amylase, for example, gave after prolonged action nearly 100% D-glucose. 

Thus, the variability of the actions of several a-amylases from different origins on elsinan is consistent with the conventional classification of amylases. The enzymes having high activities on the relatively lower maltosaccharides, such as maltotetraose and maltopentaose, are likely to hydrolyze elsinan. On the other hand, the incapability of certain a-amylases, e. g., the liquefying type amylases, may be due to their affinities to higher maltosaccharides. This can be supported by the fact that Taka amylase shows a lower activity to yield particular tetrasaccharide and heptasaccharide. 

A large fluorescence enhancement of 2-(4-toluidinylnaphthalene)-6-sulphonate caused by amylose decreases as the substrate is degraded by amylase.This property was used to follow the enzymatic hydrolysis of amylase and to analyse the action pattern of six kinds of amylases, porcine pancreatic, Taka-amylase A, two bacterial a-amylases, soybean 3-amylase, znd Rhizopus nivewj glucoamylase (seep. 477). 

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