The following is a description of an enzyme called superoxide dismutase. Refer to this paragraph to answer the following question. Superoxide dismutase is an enzyme that detoxifies a free radical called superoxide. This radical is responsible for causing injury during reperfusion after a heart attack, and is also thought to play a role in Parkinson's Disease.^a Depending on what organism the protein is found in, it occurs either as a dimer or tetramer of identical subunits.^b The subunits are mostly $\alpha$ -helical with some β-sheet near the C-terminus.^c A metal binding site for manganese, iron, nickel or copper/zinc is composed of residues from both the N-terminus and the C-terminus.^d These residues are: His-26, His-81, Asp-167, His-171.^e
Which statement refers to quaternary structure?

Question

The following is a description of an enzyme called superoxide dismutase. Refer to this paragraph to answer the following question. Superoxide dismutase is an enzyme that detoxifies a free radical called superoxide. This radical is responsible for causing injury during reperfusion after a heart attack, and is also thought to play a role in Parkinson's Disease.^a Depending on what organism the protein is found in, it occurs either as a dimer or tetramer of identical subunits.^b The subunits are mostly

\alpha

-helical with some β-sheet near the C-terminus.^c A metal binding site for manganese, iron, nickel or copper/zinc is composed of residues from both the N-terminus and the C-terminus.^d These residues are: His-26, His-81, Asp-167, His-171.^e
Which statement refers to quaternary structure?

Quizplus · Accepted Answer

Quaternary structure refers to the arrangement of multiple subunits to form a larger protein complex. In the description, it is stated that superoxide dismutase occurs either as a dimer or a tetramer of identical subunits, which refers to its quaternary structure. Therefore, statement b is the correct choice as it describes the subunit structure and arrangement in the protein complex. The other statements describe the secondary and tertiary structure of the enzyme, as well as the metal binding site.

The Following Is a Description of an Enzyme Called Superoxide α\alphaα

The Following Is a Description of an Enzyme Called Superoxide $\alpha$