A Hg (II) induced conformational change in penicillinase

Penicillinase (E.C. 3.5.2.6) from Bacillus cereus 569/H is inhibited by Hg(II). The inhibition is characterized by non-competitive kinetics and can be reversed by EDTA. A Hg(II) induced conformational change is indicated because: (1) The EDTA regenerated activity is unstable and is rapidly converted to an iodine-sensitive state, and (2) An irreversible change in the circular dichroism spectrum at 222 nm is found.