FTP, identify this functional group from organic chemistry formerly known as mercaptan and consisting of a sulfur atom bonded to a hydrogen atom.
Recent studies have shown that infectivity of the cytomegalovirus may require this functional group in its free form.  It can be qualitatively detected using lead(II) acetate, which produces a yellow solid if this functional group is present.  They are oxidized by mild oxidizing agents such as molecular iodine to produce disulfides, and cysteine is unique in that it is the only amino acid to bear this functional group.  FTP, identify this functional group from organic chemistry formerly known as mercaptan and consisting of a sulfur atom bonded to a hydrogen atom.
Recent studies have shown that infectivity of the cytomegalovirus may require this functional group in its free form.  
thiol (accept mercaptan on early buzz)