2 publications

2 publications

A Cofactor Approach to Copper-Dependent Catalytic Antibodies

Janda, K.D.; Nicholas, K.M.

Proc. Natl. Acad. Sci. U. S. A. 2002, 99, 2648-2653, 10.1073/pnas.052001099

A strategy for the preparation of semisynthetic copper(II)-based catalytic metalloproteins is described in which a metal-binding bis-imidazole cofactor is incorporated into the combining site of the aldolase antibody 38C2. Antibody 38C2 features a large hydrophobic-combining site pocket with a highly nucleophilic lysine residue, LysH93, that can be covalently modified. A comparison of several lactone and anhydride reagents shows that the latter are the most effective and general derivatizing agents for the 38C2 Lys residue. A bis-imidazole anhydride (5) was efficiently prepared from N-methyl imidazole. The 38C2–5-Cu conjugate was prepared by either (i) initial derivatization of 38C2 with 5 followed by metallation with CuCl2, or (ii) precoordination of 5 with CuCl2 followed by conjugation with 38C2. The resulting 38C2–5-Cu conjugate was an active catalyst for the hydrolysis of the coordinating picolinate ester 11, following Michaelis–Menten kinetics [kcat(11) = 2.3 min−1 and Km(11) 2.2 mM] with a rate enhancement [kcat(11)kuncat(11)] of 2.1 × 105. Comparison of the second-order rate constants of the modified 38C2 and the Cu(II)-bis-imidazolyl complex k(6-CuCl2) gives a rate enhancement of 3.5 × 104 in favor of the antibody complex with an effective molarity of 76.7 M, revealing a significant catalytic benefit to the binding of the bis-imidazolyl ligand into 38C2.

Metal: Cu
Ligand type: Bisimidazol
Host protein: Antibody 38C2
Anchoring strategy: Covalent
Optimization: Genetic
Max TON: ---
ee: ---
PDB: ---
Notes: ---

A Highly Specific Metal-Activated Catalytic Antibody

Janda, K.D.; Lerner, R.A.

J. Am. Chem. Soc. 1993, 115, 4906-4907, 10.1021/ja00064a068


Metal: Zn
Ligand type: Undefined
Host protein: IgG 84A3
Anchoring strategy: Undefined
Optimization: ---
Max TON: ---
ee: ---
PDB: ---
Notes: Substrate specificty