Final answer:
To create a disulfide bridge, it is necessary to remove two hydrogen atoms from the thiol groups of cysteine residues, allowing the formation of an S-S bond through an oxidation reaction.
Step-by-step explanation:
To make a disulfide bridge, it's necessary to remove two hydrogen atoms from two cysteine molecules. When this occurs, the sulfur atom in each cysteine's sulfhydryl (-SH) group loses its bond to a hydrogen and forms a new bond with a sulfur from another cysteine, creating an S-S bond. This process is an oxidation reaction that involves the oxidation of thiol groups into a disulfide linkage, which is vital for the establishment of a protein's tertiary structure.
Specifically, this oxidation of the thiol groups can be achieved by using oxidizing agents, such as iodine, bromine, or oxygen. The oxidized thiol groups transform into a disulfide bond, which can substantially affect protein folding and stability.
Therefore, the correct answer to the question is B. remove two H atoms, because in the process of forming a disulfide bridge, each thiol group of the cysteine residues loses a hydrogen atom.