Enzyme preparations have penetrated into all aspects of our lives due to their high efficiency, safety, non-toxic side effects and low environmental impact. For example, the bread we eat, the juice and beverage we drink, the seasoning for cooking, and the paper documents we use can all use enzyme preparations. Therefore, understanding the chemical nature of enzyme preparations is of great significance for the rational and correct use of enzyme preparations. We need to understand several factors that affect the catalytic action of enzyme preparations.
1. PH valuernEach enzyme exhibits high activity only in a specific pH range, which is the optimal pH value for enzyme action. Generally speaking, enzymes are most stable at the optimum pH value, so the pH value at which the enzyme acts is also its stable pH value. If the pH value of the enzyme reaction is too high or too low, the enzyme will be irreversibly damaged, and the stability and activity will decrease, or even inactivation. Different enzymes have different optimum pH ranges, including acidic, neutral, and alkaline. For example, according to the optimal pH value of protease action, it is often divided into acid protease, neutral
protease and alkaline protease. The pH value of enzyme action is also a parameter measured under certain conditions. The temperature or substrate is different, the optimal pH of enzyme action is different, the higher the temperature, the narrower the stable pH range of enzyme action. Therefore, in the process of enzyme-catalyzed reaction, the pH value of the reaction must be strictly controlled.
2. TemperaturernUnder certain conditions, each enzyme has an optimal temperature at which the enzyme activity is the highest and the effect is the best. The increase in the speed of the enzyme catalytic reaction and the thermal denaturation loss of the enzyme activity reach a balance. This temperature is the optimum temperature for enzyme action. Each enzyme has a stable activity temperature. At this temperature, under a certain time, pH and enzyme concentration, the enzyme is relatively stable, and there is no or very little activity decline. This temperature is the stable temperature of the enzyme. Acting beyond the stable temperature, the enzyme will be inactivated rapidly.
3. Enzyme Concentration and Substrate ConcentrationrnUnder certain conditions of temperature, pH and enzyme concentration, the substrate concentration is the main factor that determines the speed of the enzyme catalytic reaction. When the substrate concentration is very low, the catalytic reaction speed of the enzyme increases rapidly with the increase of the substrate concentration. As the substrate concentration increases, the reaction speed slows down and no longer increases in direct proportion. The relationship between the substrate concentration and the rate of the enzyme-catalyzed reaction can generally be expressed by the Michaelis equation. Sometimes the substrate concentration is very high, and the enzyme reaction speed will decrease due to substrate inhibition. When the substrate concentration greatly exceeds the enzyme concentration, the enzyme-catalyzed reaction speed is generally proportional to the enzyme concentration. In addition, if the enzyme concentration is too low, the enzyme sometimes becomes ineffective, making the reaction impossible. In the enzyme-catalyzed reaction in food processing, the amount of enzyme is generally much less than the amount of substrate, and the cost factor of enzyme should also be considered.
4. InhibitorrnMany substances can weaken, inhibit, or even destroy the action of enzymes. These substances are called
enzyme inhibitors. Such as heavy metal ions (Fe3+, Cu2+, Hg+, Pb+, etc.), carbon monoxide, hydrogen sulfide, organic cations, ethylenediamine and tetraacetic acid.
5. ActivatorsrnMany substances have the effect of protecting and increasing enzyme activity, or promoting the conversion of inactive enzyme proteins into active enzymes. These substances are collectively called enzyme activators. Activators can be divided into three categories: The first category is inorganic ions, such as Na+, K+, Ca2+, Mg2+, Cu2+, Co2+, Zn2+ and other cations, and Cl-, NO3-, PO43-, SO42- and other anions. The second category is organic matter with smaller molecules, mainly vitamin B family and its derivatives. The third category is high molecular substances with protein properties. The activator has a similar effect on the enzyme-catalyzed reaction rate and the concentration of the substrate, but it is rarely used in actual production.
6. Storage EnvironmentrnEnzyme preparations are in a dormant state in a low temperature environment. To keep the enzymes long-term storage without losing activity, the enzyme activity will be lost 5-10%/6 months when stored at 10°C, and 10-15%/6 months will be lost when stored at room temperature. So the key lies in the dry environment and low temperature. Both heat and light can easily inactivate enzymes. Therefore, enzyme preparations should be stored airtightly at low temperatures and protected from light. In addition, the higher the moisture content of the enzyme preparation, the easier it is to inactivate, so the general powdered enzyme preparation is easy to store and transport. In addition, some metal ions can also cause enzyme inactivation or inhibit enzyme activity. Avoid choosing metal ion containers to store enzyme preparations.