In the small peptide Cys1-Asn-Cys2-Lys-Ala-Pro-Cys3-Ala-Arg-Cys4-Gln-His, there are three possible arrangements of disulfide bonds between two pairs of cysteine residues that will result in two disulfide bonds. One of these combinations corresponds to disulfide bonds between Cys1 and Cys3 and between Cys2 and Cys4. What are the other two combinations of cysteine pairs that would result in two disulfide bonds? To identify the correct arrangement of disulfide bonds, the peptide was treated with the protease trypsin, which generated two oligopeptides under nonreducing conditions that preserve the disulfide bonds. Considering that trypsin cleaves peptide bonds on the C-terminal side of Arg and Lys residues, what is the correct arrangement of disulfide bonds that must exist in the small polypeptide to result in two oligomeric products?