Which of the following sets of amino acid residues constitutes the catalytic triad in chymotrypsin?  

Enzymes can accelerate reaction rates by factors of 10⁸–10¹² compared to the uncatalyzed reaction in water. Which of the following best explains the molecular basis for such an extraordinary rate enhancement?  

The following is the crystal structure of the T-state of hemoglobin, identify the residue “X” in the following image:    

An enzyme catalyzes the conversion of substrate S to product P following classic Michaelis–Menten kinetics, with a Km of 4 mM and a Vmax of 200 μmol/min. When 8 mM of the inhibitor is added, the apparent Km increases to 12 mM while Vmax remains the same. Which of the following statements is most accurate regarding the inhibitor’s properties and the kinetic consequences of its binding?  

Hemoglobin’s ability to load oxygen in the lungs and unload it in metabolically active tissues is governed by two key phenomena: the Bohr effect and positive cooperativity. Which of the following options best describes how these two mechanisms interact to optimize oxygen transport?  

Which of the following options correctly pairs an immunoglobulin class with its heavy chain designation and its primary location or function?  

Given the following energy diagram, how many intermediates formed in this chemical reaction?  

Which amino acid is negatively charged?

Which type of PTM usually occurs on the side chains of amino acids  S, T, or Y?

In a groundbreaking study that earned Chris Anfinsen the 1972 Nobel Prize in Chemistry, researchers investigated the folding behavior of ribonuclease A, a small protein containing eight cysteine residues that normally form four specific disulfide bonds. The experiment involved completely denaturing the enzyme by incubating it in urea along with 2-mercaptoethanol, a reducing agent that breaks disulfide bonds. Under these harsh conditions, the protein lost its secondary and tertiary structure, and all disulfide bonds were reduced. Remarkably, when the urea and 2-mercaptoethanol were removed, ribonuclease A spontaneously refolded into its native conformation, reestablishing the correct disulfide bonds. This result demonstrated that the protein’s amino acid sequence alone contains all the information required for it to attain its native, functional three-dimensional structure. Based on the passage above, which of the following conclusions is best supported by the ribonuclease refolding experiment?