Characteristics of Mesothermal Alpha Glucoamylase

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Characteristics of Mesothermal Alpha Glucoamylase

Mesothermal alpha glucoamylase is a kind of hydrolase and a biocatalyst for starch hydrolysis. According to the degradation mode, it can be divided into alpha-amylase, beta-amylase, glucoamylase, isoamylase and cyclodextrin-producing enzyme.

When mesothermal alpha glucoamylase hydrolyzes starch long chain molecules into short chain molecules, it breaks off the alpha-1,4 glycoside bonds in starch macromolecules in an irregular way to form dextrin and oligosaccharides. Because the carbon atom in the end of the product is alpha-conformation, it is called alpha-amylase. Most alpha-amylases (except some varieties) can not cut off the alpha-1,6 glycoside bonds, nor can they. At present, alpha-amylase is widely used in food, brewing, pharmaceuticals and textiles. When hydrolyzing starch with alpha-amylase, attention should be paid to hydrolysis conditions. The main factors affecting the activity of alpha-amylase are pH, temperature and metal ions.

In general, the activity of mesothermal alpha glucoamylase is relatively stable when the pH value is 5.5-8.0. When the pH value is less than 4, the enzyme is prone to lose its activity. However, some alpha-amylases are acidic or alkaline. For example, the most suitable pH value of alpha-amylase produced by melaspergillus is 4. When the pH value is 2.5 and the temperature is 40 C, the enzyme still has certain activity after 30 minutes of treatment. However, when the pH value was 7 and the temperature was 55 C, the activity of a-amylase was almost inactivated after 15 minutes of treatment. On the contrary, the activity of a-amylase produced by mitroxobin did not lose after 15 minutes treatment at pH 7 and temperature 55 ℃, but completely disappeared at pH 2.5.

At present, the main alpha-amylases used are medium temperature resistance (60-70 ℃) and high temperature resistance (90-95 ℃). According to the kinetics analysis of enzyme reaction, the reaction speed increases 1-2 times with the increase of temperature 10 ℃, so they are high temperature resistant.

Mesothermal alpha glucoamylase has the advantages of fast reaction, high efficiency and low cost. Alpha-amylase is a kind of metallo-enzyme. Ca2+ keeps a proper conformation of a-amylase to maintain its maximum activity and stability. In addition to Ca2+, other divalent alkali metal ions Ba2+, Mg2+also maintain the activity of a-amylase. Mesothermal alpha glucoamylase is suitable for high temperature conditions of production process. It is necessary to add some stabilizers such as Ca2+, but the stability of high temperature resistant alpha-amylase is very good when the concentration of Ca2+ is very low. In practical use, there is no need to add stabilizers such as Ca2+.

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