Sulfhydryl refers to a functional group in organic chemistry that consists of a sulfur atom bonded to a hydrogen atom, represented as -SH. This group is important in biochemistry because it can form disulfide bonds, which are crucial for the stability and structure of proteins. In biological systems, sulfhydryl groups are found in amino acids like cysteine, which plays a key role in protein folding and function. The presence of sulfhydryl groups can also influence the reactivity of molecules, making them significant in various biochemical processes, including enzyme activity and cellular signaling.