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  • External and internal electrostatic potentials of cholinesterase models.

External and internal electrostatic potentials of cholinesterase models.

Journal of molecular graphics & modelling (1998-06-26)
C E Felder, S A Botti, S Lifson, I Silman, J L Sussman
ABSTRACT

The electrostatic potentials for the three-dimensional structures of cholinesterases from various species were calculated, using the Delphi algorithm, on the basis of the Poisson-Boltzmann equation. We used structures for Torpedo californica and mouse acetylcholinesterase, and built homology models of the human, Bungarus fasciatus, and Drosophila melanogaster acetylcholinesterases and human butyrylcholinesterase. All these structures reveal a negative external surface potential, in the area around the entrance to the active-site gorge, that becomes more negative as the rim of the gorge is approached. Moreover, in all cases, the potential becomes increasingly more negative along the central axis running down the gorge, and is largest at the base of the gorge, near the active site. Ten key acidic residues conserved in the sequence alignments of AChE from various species, both in the surface area near the entrance of the active-site gorge and at its base, appear to be primarily responsible for these potentials. The potentials are highly correlated among the structures examined, down to sequence identities as low as 35%. This indicates that they are a conserved property of the cholinesterase family, could serve to attract the positively charged substrate into and down the gorge to the active site, and may play other roles important for cholinesterase function.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Acetylcholinesterase human, recombinant, expressed in HEK 293 cells, lyophilized powder, ≥1,000 units/mg protein (Lowry)
Sigma-Aldrich
Acetylcholinesterase from human erythrocytes, buffered aqueous solution, ≥500 units/mg protein (BCA)
Sigma-Aldrich
Acetylcholinesterase from Electrophorus electricus (electric eel), Type V-S, lyophilized powder, ≥1,000 units/mg protein
Sigma-Aldrich
Acetylcholinesterase from Electrophorus electricus (electric eel), Type VI-S, lyophilized powder, 200-1,000 units/mg protein