Many enzymes are inhibited irreversibly by heavy-metal ions such asHg2+, Cu2+, or Ag+, which can react with essential sulfhydrylgroups to form mercaptides, e.g.,
E-SH + Ag+ → E-S-Ag + H+
The affinity for Ag+ for sulfhydryl groups is so great that Ag+ canbe used to titrate -SH groups quantitatively. Just enough AgNO3 wasadded to a 10 mL solution containing 1.0 mg/mL of pure enzyme tocompletely inactivate the enzyme. A total of 0.342 ?mol AgNO3 wasrequired.
(a) Calculate the minimum molecular weight of the enzyme.
(b) Why does the value obtained in this way give only the minimummolecular weight?