HIV-1 protease is an enzyme made by the HIV virus. The enzyme consists of two identical chains, each containing $99$ amino acids. In every chain, amino acids $25$, $26$ and $27$ in the sequence make up part of the active site. Which orders of protein structure determine the shape of the active site?
- Aprimary, secondary, tertiary and quaternary
- Bprimary, secondary and tertiary only
- Cprimary and quaternary only
- Dquaternary only