Soybean 3-amylase

Amylase has been prepared from defatted hawk eye soybean flour. The enzyme-concentration dependence of the initial velocity for the hydrolytic reaction was investigated at pH 5.4 in a range of the enzyme concentrations and it was found that the initial velocity was proportional to the enzyme concentration in this range. The hydrolyses of maltodextrin (DPn = 74.4) and soluble starch catalysed by soybean /3-amylase were investigated in the pH range from 3.0 to 9.1 at 25 C, and and kjnax each substrate were determined at each pH. The pH-rate profile showed a bell-shaped curve, and the pH optimum was at 5.85. From Dixon plots of V and the pAT values were found to be 3.5 and... 

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). 

As shown above, the /3-amylases cannot cleave or by-pass the 1- 6 glu-cosidic linkages of amylopectin or glycogen. There is an indication from their action that amylose also has links other than the 1- 4 a-glucosidic linkages (100), Whereas crude /3-amylase can completely degrade pure amylose if retrogradation is avoided, purified /3-amylases (crystalline sweet potato and an amorphous soybean /3-amylase) are reported to degrade amylose fractions from several sources only to the extent of 70%. A /3-glu-cosidase, Z-enzyme, was obtained from the crude soybean amylase which was able to attack the anomalous links. 

Amylases are exoen2ymes that attack amylose chains and result in the successive removal of maltose units from the nonreducing end. In the case of amylopectin, the cleaving stops two to three glucose units from the a-1,6-branching points. ( -Amylase [9000-91-3] is used for the production of maltose symps and for adjunct processing in breweries. The most important commercial products are made from barley or soybeans. 

There is evidence that protease inhibitors selectively regulate the activity of specific digestive enzymes at the level of gene expression (Rosewicz et al., 1989). Specifically, soybean trypsin inhibitor increases secretion of proteases, including a form of trypsin that is resistant to inhibition but does not cause an increase in amylase secretion. Although the relationships between protease inhibitors and exocrine pancreatic secretion have received the most attention, pancreatic secretion is increased when potato fiber is added to the diet (Jacob et al., 2000), although the mechanism and signaling pathway have not been elucidated. 

Tannins are present in some varieties of canola but only at very low levels (Blair and Reichert, 1984). Canola, rapeseed and soybean hull tannins are not capable of inhibiting a-amylase (Mitaru et al, 1982), in contrast to those in other feedstuffs such as sorghum. Sinapine is the major phenolic constituent of canola and although bitter-tasting (Blair and Reichert, 1984) is not regarded as presenting any practical problems in poultry feeding except possibly for that noted above with brown-shelled layers. 

Maltose (3-amylases are primarily found in plants and have been isolated from sweet potatoes,27 soybeans,28 barley29 and wheat.30 Maltose (3-amylases are also elaborated by bacteria, e.g. by Bacillus polymyxa,31 B. megaterium,32 B. cereus33 and Pseudomonas sp. BQ6.34 These (3-amylases all produce (3-maltose and a high molecular weight (3-limit dextrin. The limit dextrins result when the enzyme reaches an a-(l—>-6) branch linkage, which it cannot pass. Approximately half of an amylopectin molecule is converted to (3-maltose the remaining half is the (3-limit dextrin. 

Soybean Beta-amylase a-Side Water866 is found II-bondedto OE2 of Glu.380 (the nucleophile), to the O atom of Asn381, and to C-l of the reaction intermediate. Loop closure on bound substrate shields the Glul86 (acid catalyst) region and all potentially reactive atoms from solvent.101... 

H,0 T. reesei CBH II Soybean A. oryzae Alpha-amylase T. reesei CBH I cellulase... 

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