When two protein chains combine to form an active protein, the structural level is ________.

Question

Quizplus · Accepted Answer

Quaternary structure refers to the arrangement of multiple protein subunits to form a larger, biologically active protein. This level of structure is specific to proteins that consist of more than one polypeptide chain. Therefore, when two protein chains combine to form an active protein, the structural level is quaternary. The other options listed refer to lower levels of protein structure, such as the arrangement of amino acids (primary), the formation of alpha-helices and beta-sheets (secondary), and the folding of individual polypeptide chains (tertiary). "Pleated" is not a valid term to describe protein structure.

When Two Protein Chains Combine to Form an Active Protein