Alpha 2-macroglobulin from horse plasma. Purification, properties and interaction with certain serine proteinases.

This paper describes the successful isolation of alpha 2-macroglobulin from horse blood plasma, its properties and interaction with certain enzymes called serine proteinases. The protein was purified using a combination of methods and tested for homogeneity.

Purification Process

• The team began by isolating alpha 2-macroglobulin from horse plasma using a precipitation method with polyethylene glycol. This is a common first step in purifying proteins, involving the separation of large particles from a solution.
• Following this, gel filtration on Sephacryl S-300 was employed. Gel filtration is a type of chromatography where molecules are separated by size, leading to further purification of the target protein.
• The team also used DE-52 cellulose chromatography. Chromatography is a technique that separates components of a mixture based on how quickly they move through a stationary phase. In cellulose chromatography, the stationary phase is cellulose.
• In the end, they achieved a 20% yield, meaning they extracted 20% of the total alpha 2-macroglobulin present in the initial sample.

Properties of alpha 2-macroglobulin

• The preparation was found to be homogeneous, meaning it consisted of identical particles, as determined by biochemical tests and immunological criteria.
• The molecular mass of the alpha 2-macroglobulin was estimated to be about 800,000. This indicates the size of the molecule, which is composed of four identical subunits.
• The isoelectric point of the preparation was 4.8. The isoelectric point is the pH at which a protein has no net charge and thus does not move in an electric field.

Interaction with Serine Proteinases

• This study further examined how alpha 2-macroglobulin interacts with a group of enzymes known as serine proteinases. These enzymes are known for breaking down proteins.
• The researchers found that two molecules of serine proteinases were bound for every molecule of alpha 2-macroglobulin inhibitor. This interaction may influence how the proteins function.