Probing the role of the hyper-reactive histidine residue of arginase.

Rat liver arginase (arginase I) is potently inactivated by diethyl pyrocarbonate, with a second-order rate constant of 113M(-1)s(-1) for the inactivation process at pH 7.0, 25 degrees C. Partial protection from inactivation is provided by the product of the reaction, l-ornithine, while nearly complete protection is afforded by the inhibitor pair, l-ornithine and borate.

Crystal structure of thrombin bound to heparin.

Thrombin is the final protease in the blood coagulation cascade and serves both pro- and anticoagulant functions through the cleavage of several targets. The ability of thrombin to specifically recognize a wide range of substrates derives from interactions that occur outside of the active site of thrombin. Thrombin possesses two anion binding exosites, which mediate many of its interactions with cofactors and substrates, and although many structures of thrombin have been solved, few such interactions have been described in molecular detail.

Design of amino acid aldehydes as transition-state analogue inhibitors of arginase.

Arginase is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of l-arginine to form l-ornithine and urea. Chiral L-amino acids bearing aldehyde side chains have been synthesized in which the electrophilic aldehyde C=O bond is isosteric with the C=N bond of L-arginine. This substitution is intended to facilitate nucleophilic attack by the metal-bridging hydroxide ion upon binding to the arginase active site.

Inhibitor coordination interactions in the binuclear manganese cluster of arginase.

Arginase is a manganese metalloenzyme that catalyzes the hydrolysis of L-arginine to form L-ornithine and urea. The structure and stability of the binuclear manganese cluster are critical for catalytic activity as it activates the catalytic nucleophile, metal-bridging hydroxide ion, and stabilizes the tetrahedral intermediate and its flanking states. Here, we report X-ray structures of a series of inhibitors bound to the active site of arginase, and each inhibitor exploits a different mode of coordination with the Mn(2+)(2) cluster.

Design of amino acid sulfonamides as transition-state analogue inhibitors of arginase.

Arginase is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of L-arginine to form L-ornithine plus urea. Chiral L-amino acids bearing sulfonamide side chains have been synthesized in which the tetrahedral sulfonamide groups are designed to target bridging coordination interactions with the binuclear manganese cluster in the arginase active site. Syntheses of the amino acid sulfonamides have been accomplished by the amination of sulfonyl halide derivatives of (S)-(tert-butoxy)-[(tert-butoxycarbonyl)amino]oxoalkanoic acids.

Human arginase II: crystal structure and physiological role in male and female sexual arousal.

Arginase is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of l-arginine to form l-ornithine and urea. The X-ray crystal structure of a fully active, truncated form of human arginase II complexed with a boronic acid transition state analogue inhibitor has been determined at 2.7 A resolution.

Structural and functional importance of first-shell metal ligands in the binuclear manganese cluster of arginase I.

Arginase is a binuclear manganese metalloenzyme that hydrolyzes l-arginine to form l-ornithine and urea. The three-dimensional structures of D128E, D128N, D232A, D232C, D234E, H101N, and H101E arginases I have been determined by X-ray crystallographic methods to elucidate the roles of the first-shell metal ligands in the stability and catalytic activity of the enzyme. This work represents the first structure-based dissection of the binuclear manganese cluster using site-directed mutagenesis and X-ray crystallography.