145. 控制盤中，器具中未接線之端點 (A)可能帶電 (B)不可能帶電 (C)永遠比大地之電位高 (D)永遠比大地之電位低

1. Protein X becomes more active in an acidic environment. When the surrounding pH decreases, protein X undergoes a conformational change, leading to its activation. Which of the following amino acid residues is most likely responsible for this pH-dependent regulation? (A) Alanine (B) Leucine (C) Histidine (D) Valine (E) Phenylalanine