Title : Electrostatic attraction by surface charge does not contribute to the catalytic efficiency of acetylcholinesterase - Shafferman_1994_EMBO.J_13_3448
Author(s) : Shafferman A , Ordentlich A , Barak D , Kronman C , Ber R , Bino T , Ariel N , Osman R , Velan B
Ref : EMBO Journal , 13 :3448 , 1994
Abstract :

Acetylcholinesterases (AChEs) are characterized by a high net negative charge and by an uneven surface charge distribution, giving rise to a negative electrostatic potential extending over most of the molecular surface. To evaluate the contribution of these electrostatic properties to the catalytic efficiency, 20 single- and multiple-site mutants of human AChE were generated by replacing up to seven acidic residues, vicinal to the rim of the active-center gorge (Glu84, Glu285, Glu292, Asp349, Glu358, Glu389 and Asp390), by neutral amino acids. Progressive simulated replacement of these charged residues results in a gradual decrease of the negative electrostatic potential which is essentially eliminated by neutralizing six or seven charges. In marked contrast to the shrinking of the electrostatic potential, the corresponding mutations had no significant effect on the apparent bimolecular rate constants of hydrolysis for charged and non-charged substrates, or on the Ki value for a charged active center inhibitor. Moreover, the kcat values for all 20 mutants are essentially identical to that of the wild type enzyme, and the apparent bimolecular rate constants show a moderate dependence on the ionic strength, which is invariant for all the enzymes examined. These findings suggest that the surface electrostatic properties of AChE do not contribute to the catalytic rate, that this rate is probably not diffusion-controlled and that long-range electrostatic interactions play no role in stabilization of the transition states of the catalytic process.

PubMedSearch : Shafferman_1994_EMBO.J_13_3448
PubMedID: 8062821

Related information

Mutation E84Q_human-ACHE    E84Q\/E292A_human-ACHE    E84Q\/D349N\/E358Q_human-ACHE    E84Q\/E292A\/D349N\/E358Q_human-ACHE    E84Q\/E285A\/E292A\/D349N\/E358Q_human-ACHE    E84Q\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E84Q\/E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E84Q\/E285A\/E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E285A_human-ACHE    E292A_human-ACHE    E292A\/D349N\/E358Q_human-ACHE    E292A\/E389Q\/D390N_human-ACHE    E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    D349N_human-ACHE    D349N\/E358Q_human-ACHE    D349N\/E358Q\/E389Q\/D390N_human-ACHE    E358Q_human-ACHE    E389Q_human-ACHE    E389Q\/D390N_human-ACHE    D390N_human-ACHE
Inhibitor E84Q_human-ACHE    E84Q\/E292A_human-ACHE    E84Q\/D349N\/E358Q_human-ACHE    E84Q\/E292A\/D349N\/E358Q_human-ACHE    E84Q\/E285A\/E292A\/D349N\/E358Q_human-ACHE    E84Q\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E84Q\/E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E84Q\/E285A\/E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E285A_human-ACHE    E292A_human-ACHE    E292A\/D349N\/E358Q_human-ACHE    E292A\/E389Q\/D390N_human-ACHE    E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    D349N_human-ACHE    D349N\/E358Q_human-ACHE    D349N\/E358Q\/E389Q\/D390N_human-ACHE    E358Q_human-ACHE    E389Q_human-ACHE    E389Q\/D390N_human-ACHE    D390N_human-ACHE    Edrophonium
Substrate E84Q_human-ACHE    E84Q\/E292A_human-ACHE    E84Q\/D349N\/E358Q_human-ACHE    E84Q\/E292A\/D349N\/E358Q_human-ACHE    E84Q\/E285A\/E292A\/D349N\/E358Q_human-ACHE    E84Q\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E84Q\/E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E84Q\/E285A\/E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    E285A_human-ACHE    E292A_human-ACHE    E292A\/D349N\/E358Q_human-ACHE    E292A\/E389Q\/D390N_human-ACHE    E292A\/D349N\/E358Q\/E389Q\/D390N_human-ACHE    D349N_human-ACHE    D349N\/E358Q_human-ACHE    D349N\/E358Q\/E389Q\/D390N_human-ACHE    E358Q_human-ACHE    E389Q_human-ACHE    E389Q\/D390N_human-ACHE    D390N_human-ACHE    Edrophonium    3,3-dimethylbutylthioacetate    Acetylthiocholine

Citations formats

Shafferman A, Ordentlich A, Barak D, Kronman C, Ber R, Bino T, Ariel N, Osman R, Velan B (1994)
Electrostatic attraction by surface charge does not contribute to the catalytic efficiency of acetylcholinesterase
EMBO Journal 13 :3448

Shafferman A, Ordentlich A, Barak D, Kronman C, Ber R, Bino T, Ariel N, Osman R, Velan B (1994)
EMBO Journal 13 :3448