Question

sulfhydryl functional groups can interact together to form disulfide bridges to stabilize a proteins shape. an increase in which amino acid, shown in the table above, would result in a more stable protein?
options: threonine, methionine, cysteine, histidine

Explanation:

Disulfide bridges in proteins are formed by the interaction of sulfhydryl groups (-SH), which are present in the amino acid cysteine. Threonine has a hydroxyl - containing side chain, methionine has a thioether group (not a sulfhydryl), and histidine has an imidazole group. Only cysteine has the sulfhydryl group needed to form disulfide bridges, so increasing cysteine would lead to more disulfide bridges and a more stable protein.

Answer:

Cysteine (the option corresponding to Cysteine among the given choices, e.g., if the options are labeled as: Threonine, Methionine, Cysteine, Histidine, then the answer is the option with Cysteine text)