3) For each of the following characteristics, will the migration of the protein speed up, slow down, or remain unchanged if you do not add SDS?
a)increase molecular weight of protein
b) increase concentration of acrylamide
c)decrease charge on protein
d) increase surface area of protein
To determine how the migration of a protein will be affected by each characteristic without adding SDS, we need to understand the principle of protein migration in gel electrophoresis.
Gel electrophoresis is a technique used to separate proteins based on their size, charge, and shape. Here, we will be discussing the migration of proteins in a polyacrylamide gel.
a) Increase molecular weight of the protein:
In gel electrophoresis, proteins are separated based on their size. Higher molecular weight proteins tend to migrate more slowly than lower molecular weight proteins. Therefore, if the molecular weight of a protein increases, its migration speed will slow down.
b) Increase concentration of acrylamide:
Acrylamide is used to make the gel in gel electrophoresis. The concentration of acrylamide affects the pore size of the gel. Higher acrylamide concentrations result in smaller pore sizes, which restrict the movement of larger proteins. Therefore, when the concentration of acrylamide increases, the migration speed of proteins, especially larger proteins, will slow down.
c) Decrease charge on the protein:
Proteins have different charges depending on their composition and pH of the buffer. In gel electrophoresis, proteins migrate towards the oppositely charged electrode. If the charge on a protein decreases, it will be less attracted to the electrode of opposite charge, resulting in slower migration.
d) Increase surface area of the protein:
The surface area of a protein does not significantly affect its migration speed in gel electrophoresis. The separation of proteins primarily depends on size and charge, not shape or surface area.
In summary:
a) Increase molecular weight: The migration speed will slow down.
b) Increase concentration of acrylamide: The migration speed, particularly for larger proteins, will slow down.
c) Decrease charge on protein: The migration speed will slow down.
d) Increase surface area of protein: The migration speed will remain unchanged.