Metalloantibodies:: Mercury(II)-dependent acyl transferases

A new approach for the elicitation of metal-dependent catalytic antibodies for ester hydrolysis is described. A coordinatively unsaturated mercury complex 1-(Hg), has been utilized as a hapten to elicit antibodies that incorporate mercury(II) as a Lewis acid cofactor. From a panel of monoclonal antibodies generated to 1-(Hg), antibody 38G2 was found to hydrolyze the ester 3 in the presence of HgCl2 [K(m)app(3) = 345 muM; K(m)app(Hg2+) = 87 muM; k(cat)app/k(uncat) = 3 x 10(2)]. This is the first example of a biocatalyst that enlists mercuric ion as a cofactor and it is anticipated that this approach will open new avenues for exploitation of metals thought previously beyond the scope of protein catalysts. (C) 2001 Elsevier Science Ltd. All rights reserved.