Question

Determine the subunit composition of a protein from the following information:Molecular mass by gel filtration: 200 kDMolecular mass by SDS-PAGE: 100 kDMolecular mass by SDS-PAGE with 2-mercaptoethanol: 40 kD and 60 kD

Answer 1

Step-by-step explanation:

The protein comprises of two 60-kD polypeptides and two 40-kD polypeptides. Each one of the 40-kD chains has a disulfide-bond, which is directly bonded to a 60-kD chain.

The 100-kD units attach noncovalently to produce a protein with a molecular mass of 200 kD.

The protein consists of 200 kD in size, and the Gel filtration doesn't affect the relationship and interaction among the various subunits in the protein.

When SDS-PAGE takes place, samples are being subjected to boiling of samples and therefore undergoing denaturation conditions. The result causes disorganization in the 100 kD units.

It implies that BME is responsible for the reduction between the R1-S-S-R2 bond between 40 kD and 60 kD to R1-SH and R2-SH, resulting in separate proteins.

However, the reducing agent (BME) main task is reducing disulfide bonds in a protein.