What Is the Structure of Amylase?

Alpha-amylase, the system name is 1,4--D-glucan glucan hydrolase, and its aliases are liquefied amylase, liquefied enzyme, and -1,4-dextrinase. Yellow-brown solid powder or yellow-brown to dark brown liquid, water content 5% ~ 8%. Soluble in water, insoluble in ethanol or ether. According to FAO / WHO regulations, there are no special restrictions on ADI ^[1] .

Alpha-amylase, the system name is 1,4--D-glucan glucan hydrolase, and its aliases are liquefied amylase, liquefied enzyme, and -1,4-dextrinase. Yellow-brown solid powder or yellow-brown to dark brown liquid, water content 5% ~ 8%. Soluble in water, insoluble in ethanol or ether. According to FAO / WHO regulations, there are no special restrictions on ADI ^[1] .

Chinese name

alpha-amylase

English name

-Amylase; 1,4--D-Glucan-glucanohydrolase

nickname

Liquefied saccharifying enzyme; liquefied amylase; alpha-amylase

CAS Registry Number

9000-90-2

EINECS registration number

232-565-6

Water soluble

Soluble in water and dilute buffer solution, almost insoluble in ethanol.

Exterior

Yellow-brown, lyophilized powder

Alpha amylase basic information

English name: -Amylase (Bacilus subtilis); 1,4--D-Glucan-glucanohydrolase
Other names: medium temperature amylase; liquefied amylase; liquefied enzyme; -1,4 dextrinase; bacterial amylase; -amylase; dextrinase ^[2] CAS number: 9000-90-2
Level: BioChemika
Vigor: 50U / mg
Definition of vitality: 1 U corresponds to the amount of enzyme which liberates 1 mole maltose per minute at pH 6.9 at 25 ° C (starch acc. To Zulkowsky, Catalog No. 85642, as substrate).
Properties: tan or off-white powder. Extraction from Bacillus subtilis Uses: Biochemical research. Can make starch liquefy quickly and generate low molecular weight. ^[3] Storage: 2 8

Alpha amylase properties

Under the protection of high concentration of starch, -amylase has strong heat resistance. When the pH value is 5.3 ~ 7.0 in the presence of proper amount of calcium salt and table salt, the temperature can still maintain a sufficiently high activity when the temperature is increased to 93 ~ 95 . To facilitate storage, an appropriate amount of calcium carbonate is often added as an anti-caking agent to prevent clumping.

Alpha-amylase can hydrolyze the -1,4-glycosidic bonds in starch. The hydrolysis products are dextrin, oligosaccharides and monosaccharides. The enzyme can quickly reduce the viscosity of gelatinized starch and become liquefied starch. Also called liquefied amylase, liquefied enzyme, -1,4-dextrinase.

When alpha-amylase uses amylopectin as a substrate, the reaction generally proceeds in two stages. First, amylose is rapidly degraded to produce oligosaccharides. At this stage, the viscosity of amylose and its ability to react with iodine quickly decrease. The reaction in the second stage is much slower than the first stage, including the slow hydrolysis of oligosaccharides to the final products glucose and maltose. Alpha-amylase produces glucose, maltose, and a series of restricted dextrin (oligosaccharides composed of 4 or more glucose groups) when acting on amylopectin, all of which contain alpha-1,6-glycosidic bonds.

The alpha-amylase molecule contains a fairly firmly bound calcium ion. This calcium ion does not directly participate in the formation of the enzyme-substrate complex. Its function is to maintain the structure of the enzyme, so that the enzyme has the greatest stability and the highest active.

The optimal pH value of -amylase is between 4.5 and 7.0 depending on the source. The optimal pH value range of -amylase obtained from human saliva and pig pancreas is relatively narrow, between 6.0 and 7.0; Bacillus subtilis - The optimum pH range of amylase is wide, between 5.0 and 7.0; the optimum pH value of Bacillus stearothermophilus-amylase is around 3.0; the optimum pH range of sorghum bud -amylase is 4.8 ~ 5.4; The optimum pH value of wheat -amylase is around 4.5. When the pH value is lower than 4, the activity decreases significantly, and when it exceeds 5, the activity decreases slowly.

According to the thermal stability of -amylase, it can be divided into high temperature resistant -amylase and medium temperature-amylase. Among the high-temperature-resistant -amylases, enzyme preparations produced by Bacillus starch liquefaction and Bacillus licheniformis have been widely used in food processing. The temperature has different effects on the activities of these two enzymes. The optimal temperature of Bacillus licheniformis-amylase is 92 ° C, while the optimal temperature of liquefied Bacillus amyloliquefaciens-amylase is only 70%, except for the difference in thermal stability. The end products of the two enzymes acting on starch are also different ^[1] .

Alpha amylase function

Hydrolyzing only the -1,4-glucoside bonds in the molecular chain of starch, cutting the starch chain into short-chain dextrin, oligosaccharides, and a small amount of maltose and glucose, rapidly reducing the viscosity of starch to achieve the purpose of "liquefaction" ^[4] .

Alpha amylase toxicology basis

(1) LD50 mice were orally administered 7375 mg / kg.

(2) ADI: Acceptable [from Aspergillus oryzae (JECFA, 1987)]; no requirement [from Bacillus subtilis, Bacillus stearothermophilus (JECFA, 1990), and Bacillus licheniformis (JECFA, 2003)].

(3) Mutagenic effect. This product has no significant accumulation in the body and no mutagenic effect ^[4] .

Alpha amylase application

Alpha-amylase is mainly used to hydrolyze starch to produce sugar, glucose and syrup, as well as to produce dextrin, beer, rice wine, alcohol, soy sauce, vinegar, fruit juice and monosodium glutamate. It is also used in the production of bread to improve the dough, such as reducing the viscosity of the dough, accelerating the fermentation process, increasing the sugar content and reducing the aging of bread. It is used for pretreatment of cereals in infant food. It is also used in vegetable processing. Dosage: Based on Bacillus subtilis alpha-amylase (6000IU / g), the added amount is about 0.1% ^[3] .