3 publications

3 publications

A Semisynthetic Metalloenzyme based on a Protein Cavity that Catalyzes the Enantioselective Hydrolysis of Ester and Amide Substrates

Distefano, M. D.

J. Am. Chem. Soc., 1997, 10.1021/JA970820K

In an effort to prepare selective and efficient catalysts for ester and amide hydrolysis, we are designing systems that position a coordinated metal ion within a defined protein cavity. Here, the preparation of a protein-1,10-phenanthroline conjugate and the hydrolytic chemistry catalyzed by this construct are described. Iodoacetamido-1,10-phenanthroline was used to modify a unique cysteine residue in ALBP (adipocyte lipid binding protein) to produce the conjugate ALBP-Phen. The resulting material was characterized by electrospray mass spectrometry, UV/vis and fluorescence spectroscopy, gel filtration chromatography, and thiol titration. The stability of ALBP-Phen was evaluated by guanidine hydrochloride denaturation experiments, and the ability of the conjugate to bind Cu(II) was demonstrated by fluorescence spectroscopy. ALBP-Phen-Cu(II) catalyzes the enantioselective hydrolysis of several unactivated amino acid esters under mild conditions (pH 6.1, 25 °C) at rates 32−280-fold above the background rate in buffered aqueous solution. In 24 h incubations 0.70 to 7.6 turnovers were observed with enantiomeric excesses ranging from 31% ee to 86% ee. ALBP-Phen-Cu(II) also promotes the hydrolysis of an aryl amide substrate under more vigorous conditions (pH 6.1, 37 °C) at a rate 1.6 × 104-fold above the background rate. The kinetics of this amide hydrolysis reaction fit the Michaelis−Menten relationship characteristic of enzymatic processes. The rate enhancements for ester and amide hydrolysis reported here are 102−103 lower than those observed for free Cu(II) but comparable to those previously reported for Cu(II) complexes.


Metal: Cu
Ligand type: Phenanthroline
Anchoring strategy: Covalent
Optimization: ---
Max TON: 1 to 8
ee: 39 to 86
PDB: ---
Notes: ---

Peroxidation of Pyrogallol by Antibody−Metalloporphyrin Complexes

Harada, A.

Inorg. Chem., 1997, 10.1021/ic9610849


Metal: Mn
Ligand type: Porphyrin
Host protein: Antibody 03-1
Anchoring strategy: Antibody
Optimization: ---
Max TON: 200
ee: ---
PDB: ---
Notes: ---

Metal: Fe
Ligand type: Porphyrin
Host protein: Antibody 03-1
Anchoring strategy: Antibody
Optimization: ---
Max TON: 300
ee: ---
PDB: ---
Notes: ---

Pyridoxamine-Amino Acid Chimeras in Semisynthetic Aminotransferase Mimics

Imperiali, B.

Prot. Eng., 1997, 10.1093/protein/10.6.691


Metal: Cu
Ligand type: Undefined
Host protein: RNase A
Anchoring strategy: Supramolecular
Optimization: Chemical
Reaction: Transamination
Max TON: ---
ee: 31
PDB: ---
Notes: ---