Introduction to the Enzymes Separation and Purification

There are two types of enzymes produced by biological cells: one type of enzymes that are produced inside the cell and then secreted outside the cell for action, called extracellular enzymes. Most of these enzymes are hydrolases. For example, the two amylases used in enzymatic production of glucose are secreted by Bacillus subtilis and root enzymes during fermentation. Such enzymes are generally high in content and easy to obtain. Another type of enzyme is produced in the cell and is not secreted outside the cell, but plays a catalytic role in the cell, which is called intracellular enzyme. A series of chemical reactions in the fermentation and production of citric acid, inosinic acid and monosodium glutamate are carried out in cells under the catalysis of a variety of enzymes. This type of enzyme is often combined with the cell structure in the cell, has a certain distribution area, and the catalyzed reaction has a certain sequence, so that many reactions can proceed in an orderly manner. The source of enzymes is mostly biological cells. Although the total amount of enzymes produced in biological cells is very high, the content of each enzyme is extremely low. For example, there are many types of hydrolases in the mid-pancreas digestion, but the content of various enzymes is very different. Therefore, when extracting a certain enzyme, you should first select the material that contains the most abundant enzyme according to your needs. For example, pancreas is a good material for extracting trypsin, chymotrypsin, amylase and lipase. Since the extraction of enzyme preparations from animal organs or plant fruits is limited by raw materials, the cost is very high if they cannot be used comprehensively. At present, the industry mostly adopts the method of cultivating microorganisms to obtain a large amount of enzyme preparations. There are many advantages of producing enzyme preparations from microorganisms. It is not restricted by climate and geographical conditions, and most of the enzymes in animals and plants can be found in microorganisms. The microorganisms multiply fast and the enzyme production is abundant. In biological tissues, in addition to a certain enzyme we need, there are often many other enzymes, general proteins and other impurities. Therefore, in order to prepare a certain enzyme preparation, it must go through the steps of enzyme separation and enzyme purification. Enzymes are proteins with catalytic activity. Protein is easy to denature, so in the purification process of enzyme should avoid using strong acid and strong base and keep the operation at a lower temperature. In the purification process, it is easier to track the whereabouts of the enzyme in the separation and purification process by measuring the catalytic activity of the enzyme. The catalytic activity of the enzyme can be used as an index for the selection of separation and purification methods and operating conditions. In each step of the entire enzyme separation and purification process, always determine the total activity and specific activity of the enzyme. Only in this way can we know how many enzymes are recovered through a certain step and how much purity has been improved, which determines the choice of a step. The separation and purification of enzymes generally includes three basic steps: extraction, purification, crystallization or preparation. First, the required enzyme is introduced into the solution from the raw material. At this time, some impurities are inevitably entrained. It is necessary to selectively separate the enzyme from the solution (or selectively remove impurities from the solution). Finally, purified enzyme preparation is made.