Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 1990 Oct;87(19):7546-50.
doi: 10.1073/pnas.87.19.7546.

Mutagenesis of essential functional residues in acetylcholinesterase

G Gibney  1 , S Camp, M Dionne, K MacPhee-Quigley, P Taylor
Affiliations
Comparative Study

Mutagenesis of essential functional residues in acetylcholinesterase

G Gibney et al. Proc Natl Acad Sci U S A. 1990 Oct.

Abstract

The cholinesterases are serine hydrolases that show no global similarities in sequence with either the trypsin or the subtilisin family of serine proteases. The cholinesterase superfamily includes several esterases with distinct functions and other proteins devoid of the catalytic serine and known esterase activity. To identify the residues involved in catalysis and conferring specificity on the enzyme, we have expressed wild-type Torpedo acetylcholinesterase (EC 3.1.1.7) and several site-directed mutants in a heterologous system. Mutation of serine-200 to cysteine results in diminished activity, while its mutation to valine abolishes detectable activity. Two conserved histidines can be identified at positions 425 and 440 in the cholinesterase family; glutamine replacement at position 440 eliminates activity whereas the mutation at 425 reduces activity only slightly. The assignment of the catalytic histidine to position 440 defines a rank ordering of catalytic residues in cholinesterases distinct from trypsin and subtilisin and suggests a convergence of a catalytic triad to form a third, distinct family of serine hydrolases. Mutation of glutamate-199 to glutamine yields an enzyme with a higher Km and without the substrate-inhibition behavior characteristic of acetylcholinesterase. Hence, modification of the acidic amino acid adjacent to the serine influences substrate association and the capacity of a second substrate molecule to affect catalysis.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Biochemistry. 1966 Jun;5(6):1983-8 - PubMed
    1. Biochem Pharmacol. 1961 Jul;7:88-95 - PubMed
    1. Biochemistry. 1967 Feb;6(2):610-20 - PubMed
    1. Biochemistry. 1974 Dec 3;13(25):5141-4 - PubMed
    1. Adv Enzymol Relat Areas Mol Biol. 1975;43:103-218 - PubMed

Publication types