Preserved Salted Black Bean,Roasted Salted Broad Beans,Preserved Black Bean With Ginger,Salt And Chilli Edamame Beans jiangmen city hongsing food co., ltd. , https://www.jmhongsing.com
　Â
The electrophoresis process must be performed in a support medium. The free-interface electrophoresis performed by Tiselius et al. in 1937 did not have a fixed support medium, so diffusion and convection were relatively strong, affecting the separation effect. Electrophoresis of a fixed support medium occurs, and the sample is subjected to an electrophoresis process in a fixed medium, thereby reducing interference effects such as diffusion and convection. The initial support media were filter paper and cellulose acetate membranes, which are currently used less in the laboratory. For a long time, small molecular substances such as amino acids, peptides, sugars, etc. are usually separated and analyzed by electrophoresis using filter paper or a thin layer of cellulose or silica gel as a medium. However, more sensitive techniques such as HPLC are generally used. Analyze. These media are suitable for separating small molecular substances, and the operation is simple and convenient. However, for complex biomacromolecules, the separation effect is poor. The introduction of gel as a supporting medium has greatly promoted the development of electrophoresis technology, making electrophoresis technology one of the important means for analyzing biological macromolecules such as proteins and nucleic acids. The gel originally used was a starch gel, but the most commonly used ones are agarose gels and polyacrylamide gels. Protein electrophoresis mainly uses polyacrylamide gels.
　Â
The electrophoresis device mainly comprises two parts: a power source and an electrophoresis tank. The power supply provides direct current, creating an electric field in the electrophoresis tank that drives the migration of charged molecules. The electrophoresis tank can be divided into two types, horizontal and vertical. Vertical plate electrophoresis is a relatively common type and is commonly used for protein separation in polyacrylamide gel electrophoresis. In the middle of the electrophoresis tank are two glass plates sandwiched together. The two sides of the glass plate are separated by plastic strips. Electrophoresis gel is prepared in the middle of the glass plate. The size of the gel is usually 12cm 14 cm and the thickness is 1mm~2? mm. The newly developed electrophoresis tank has a smaller and thinner surface to save reagents and shorten electrophoresis time. When making the glue, a plastic comb is placed in the gel solution, and after the gel is polymerized, it is removed to form a groove of the upper sample. For horizontal electrophoresis, the gel is spread on a horizontal glass or plastic plate, and the gel and running buffer are connected by a thin layer of wet filter paper, or the gel is directly immersed in the buffer. Since the change in pH causes a change in the charge of the charged molecule, which in turn affects the rate of electrophoretic migration, the electrophoresis process should be carried out in a suitable buffer which maintains the chargeability of the analyte to be stabilized.
　Â
In order to better understand how charged molecules are separated during electrophoresis, the basic principle of electrophoresis is briefly introduced below. Applying a certain voltage (V) to the two parallel electrodes produces an electric field strength (E) in the middle of the electrode, and L is the distance between the electrodes.
　Â
In a dilute solution, the force of the electric field on the charged molecule (F) is equal to the product of the net charge and the electric field strength. This force causes the charged molecules to move toward the opposite electrode of their charge. During the movement, the molecules are hindered by the viscous forces of the medium. The size of the viscous force (F') is related to the size of the molecule, the shape, the pore size of the electrophoretic medium, and the viscosity of the buffer, and is proportional to the moving speed of the charged molecules. For spherical molecules, the size of F' obeys Stokes' law, namely: F'=6πrηυ where r is the radius of the spherical molecule, η is the viscosity of the buffer, and υ is the electrophoresis speed (υ=d / t, the distance of particle motion per unit time, cm / s). When the charged molecule moves at a constant speed: F = F', q?E = 6πrηυ It can be seen that the mobility is proportional to the net charge of the charged molecule and inversely proportional to the size of the molecule and the viscosity of the buffer.
When the molecular weight of a protein is determined by SDS-polyacrylamide gel electrophoresis, the relative mobility mR is actually used. Charged molecules have different migration velocities during electrophoresis due to their different charge and shape sizes, forming different zones arranged in sequence and being separated. Even if two molecules have similar charges, if they have different molecular sizes, because of the different resistance they are subjected to, the migration speed is different and can be separated during electrophoresis. Some types of electrophoresis rely almost entirely on the charge of the molecule to separate, such as isoelectric focusing electrophoresis; while some types of electrophoresis rely mainly on the difference in molecular size, ie the resistance generated during electrophoresis, to separate, such as SDS- Polyacrylamide gel electrophoresis. The separated sample is stained by various methods, or if the sample is radiolabeled, it can be detected by a method such as autoradiography.
Introduction to electrophoresis technology
Electrophoresis refers to the process by which charged particles migrate under the action of an electric field. Many important biological molecules, such as amino acids, peptides, proteins, nucleotides, nucleic acids, etc., have ionizable groups, which can be positively or negatively charged at a certain pH. Under the action of an electric field, these are charged. The molecule moves toward the opposite polarity of the electrode it carries. The electrophoresis technology utilizes the electric field to separate, identify or purify the charged molecules due to the different molecular charging properties of the sample to be separated and the difference in the size and shape of the molecules themselves. technology.