Some enzymes have one or more sulfhydryl (thiol) groups that are important to enzymatic activity but that can react upon standing in solution to form inactive disulfide bonds. thiol reagents, such as 1,4-dithiothreitol (dtt), are often added to the solutions of such proteins to protect them from this reaction and to reverse it when it occurs. (the reverse reaction works best at slightly alkaline ph.) draw the product formed when dtt reacts with a protein disulfide bond to liberate the free thiol groups. which of the following occurs in this reaction? (check all that apply)the protein disulfide is oxidizedthe protein disulfide is reduceddtt is reduceddtt is oxidized