Anionic subsites of the catalytic center of acetylcholinesterase from Torpedo and from cobra venom.

Kreienkamp, Hans‐Jürgen; Weise, Christoph; Raba, Raivo; Aaviksaar, Aavo; Hucho, Ferdinand

doi:10.1073/pnas.88.14.6117

Cited by 45 publications

(23 citation statements)

References 46 publications

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“…At substrate concentrations greater than 1 mM krait venom AChE hydrolytic property was reduced ( Figure 1). Similar substrate inhibition was observed with other snake venom acetylcholinesterase (10,24,25).…”

Section: Discussionsupporting

confidence: 66%

Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

Ahmed¹,

Latif²,

Khan³

et al. 2012

J. Venom. Anim. Toxins incl. Trop. Dis

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This study analyses venom from the elapid krait snake Bungarus sindanus, which contains a high level of acetylcholinesterase (AChE) activity. The enzyme showed optimum activity at alkaline pH (8.5) and 45°C. Krait venom AChE was inhibited by substrate. Inhibition was significantly reduced by using a high ionic strength buffer; low ionic strength buffer (10 mM PO 4 pH 7.5) inhibited the enzyme by 1. 5mM AcSCh, while high ionic strength buffer (62 mM PO 4 pH 7.5) inhibited it by 1 mM AcSCh. Venom acetylcholinesterase was also found to be thermally stable at 45°C; it only lost 5% of its activity after incubation at 45°C for 40 minutes. The Michaelis-Menten constant (Km) for acetylthiocholine iodide hydrolysis was found to be 0.068 mM. Krait venom acetylcholinesterase was also inhibited by ZnCl 2 , CdCl 2 , and HgCl 2 in a concentrationdependent manner. Due to the elevated levels of AChE with high catalytic activity and because it is more stable than any other sources, Bungarus sindanus venom is highly valuable for biochemical studies of this enzyme.

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Section: Discussionsupporting

confidence: 66%

Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

Ahmed¹,

Latif²,

Khan³

et al. 2012

J. Venom. Anim. Toxins incl. Trop. Dis

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“…In particular, AChE may be purified in significant quantities from the venom of Bungarus fasciatus. In this report, we show that this enzyme presents a strong sequence homology with AChEs from various invertebrate and vertebrate species, in agreement with previous studies on AChE from the venom of Naja naja oxiana [4,5]. It differs, however, from AChEs from other vertebrate tissues by the fact that it consists entirely of soluble, non-amphiphilic monomers.…”

Section: Ache Assaysupporting

confidence: 76%

Acetylcholinesterase from Bungarus venom: a monomeric species

Cousin¹,

Créminon²,

Grassi³

et al. 1996

FEBS Letters

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The venom of Bungarusfasciatus, an Elapidae snake, contains a high level of AChE activity. Partial peptide sequences show that it is closely homologous to other AChEs. Bungarus venom AChE is a non-amphiphilic monomeric species, a molecular form of AChE which has not been previously found in significant levels in other tissues. The composition of carbohydrates suggests the presence of N-glycans of the 'complex' and 'hybrid' types. Ion exchange chromatography, isoelectric focusing and electrophoresis in non-denaturing and denaturing conditions reveal a complex microheterogeneity of this enzyme, which is partly related to its glyeosylation.

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“…This is in apparent contradiction to a previous report from Kreienkamp et al (1991) who claimed that cobra venom acetylcholinesterase (Nuju nuju oxiunu) is devoid of a peripheral site.…”

Section: Discussioncontrasting

confidence: 54%

Characterization of Monoclonal Antibodies that Strongly Inhibit Electrophorus Electricus Acetylcholinesterase

Remy

Frobert

Grassi

1995

European Journal of Biochemistry

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In this study, we describe three different monoclonal antibodies (mAbs Elec-403, Elec-408, and Elec-410) directed against Electrophorus electricus acetylcholinesterase (AChE) which were selected as inhibitors for this enzyme. Two of these antibodies , recognized overlapping but different epitopes, competed with snake venom toxin fasciculin for binding to the enzyme, and thus apparently recognized the peripheral site of AChE. In addition, the binding of Elec-403 was antagonized by 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide (BW284C51) and propidium, indicating that the corresponding epitope encompassed the anionic site involved in the binding of these lowmolecular-mass inhibitors. The third mAb (Elec-408), was clearly bound to another site on the AChE molecule, and its inhibitory effect was cumulative with those of Elec-403, Elec-410, and fasciculin. All mAbs bound AChE with high affinity and were as strong inhibitors with an apparent K, value less than 0.1 nM. Elec-403 was particularly efficient with an inhibitory activity similar to that of fasciculin. Inhibition was observed with both charged (acetylthiocholine) and neutral substrates (o-nitrophenyl acetate) and had the characteristics of a non-competitive process. Elec-403 and Elec-410 probably exert their effect by triggering allosteric transitions from the peripheral site to the active site. The epitope recognized by mAb Elec-408 has not been localized, but it may correspond to a new regulatory site on AChE.Keywords. acetylcholinesterase ; inhibitory monoclonal antibodies ; peripheral site ; fasciculin.Acetylcholinesterase (acetylcholine acetylhydrolase, AChE) is widely distributed in the central and peripheral nervous systems where it plays a critical role in quickly hydrolyzing the neurotransmitter acetylcholine. Hydrolysis is the result of nucleophilic attack of the carbonyl carbon by a serine residue in the enzyme active center and involves charge transfer via a histidine residue. In accordance with its biological function, a remarkable feature of AChE is its high catalytic rate in cleaving acetylcholine. AChE works at a rate approaching that of a diffusion-controlled process (Rosenbeny, 1975 ;Quinn, 1987). Even if the enzyme preferentially acts on its natural substrate, it can also efficiently hydrolyze neutral acetic esters including indophenyl acetate, naphthyl acetate, indoxyl acetate, and nitrophenyl acetate (Quinn, 1987). Until recently, it was usually considered that the catalytic center of AChE! was composed of an esteratic and an anionic subsite. The esteratic subsite contains the active serine and is the target for irreversible inhibitors, such as organo-phosphorus and carbamate compounds, which block enzyme activity by forming covalent bonds between phosphoryl or carbamoyl groups and the serine residue. The anionic subsite is implicated in orientating the positively charged substrate in the active center. Many reversible inhibitors that possess quater-

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Anionic subsites of the catalytic center of acetylcholinesterase from Torpedo and from cobra venom.

Cited by 45 publications

References 46 publications

Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

Acetylcholinesterase from Bungarus venom: a monomeric species

Characterization of Monoclonal Antibodies that Strongly Inhibit Electrophorus Electricus Acetylcholinesterase

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