Question

You are researching a cytoplasmic protein associated with a nerve disorder. The native form of the enzyme appears to be globular protein; however, when a sample of the purified protein is treated with a chemical that reduces disulfide bonds, the enzymatic activity decreases dramatically and multiple globular proteins can be detected in the sample. What does this tell you about the protein?

Answer 1

Answer:

This signifies that the protein primarily comprises multiple polypeptide chains connected together with the help of disulfide bonds. The enzymes may be found in the form of dimers, trimers, or tetramers. Various examples of dimers, trimers, and tetramer proteins are known, of them, NEMOs dimers are considered to be held by disulfide bonds.  

Thus, it can be hypothesized that the enzyme under examination is a multimer held in combination by disulfide bonds, with each comprising catalytic sites. On breaking of disulfide bonds, the enzyme dissociates into its many single units.  

This illustrates the reduction in catalytic activity. Each active site in a single unit will work, however, at a gradual rate. This also shows detection of multiple globular proteins after disulfide reduction.