Search results for: Dov Barak

Items from 1 to 20 out of 20 results

article

Ligand-G Protein Allosteric Communication through Internal Waters in GPCR Complexes

Roman Osman, Jose Carlos Gomez, Mihaly Mezei, Dov Barak, more

Biophysical Journal > 2015 > 108 > 2 Supplement 1 > 363a-364a

article

The Role of Internal Water in GPCR Complexes

Roman Osman, Mihaly Mezei, Dov Barak, Arnau Cordomi, more

Biophysical Journal > 2013 > 104 > 2 Supplement 1 > 41a

article

Evaluation of Homology Modeling of G-Protein-Coupled Receptors in Light of the A _2A Adenosine Receptor Crystallographic Structure

Andrei A. Ivanov, Dov Barak, Kenneth A. Jacobson

Journal of Medicinal Chemistry > 2009 > 52 > 10 > 3284 - 3292

article

Flexibility versus “rigidity” of the functional architecture of AChE active center

Avigdor Shafferman, Dov Barak, Dana Stein, Chanoch Kronman, more

Chemico-Biological Interactions > 2008 > 175 > 1-3 > 166-172

Functional architecture of the AChE active center appears to be characterized by both structural “rigidity”, necessary to stabilize the catalytic triad as well as by flexibility in accommodating the different, high affinity AChE ligands. These seemingly conflicting structural properties of the active center are demonstrated through combination of structural methods with kinetic studies of the enzyme...

article

Function-specific blockage of M1 and M3 muscarinic acetylcholine receptors by VX and echothiophate

Zipora Pittel, Dov Barak, Yoffi Segall

Brain Research > 2006 > 1085 > 1 > 102-110

Certain organophosphate (OP) cholinesterase inhibitors (ChEIs) are also known to bind to the muscarinic acetylcholine receptor (mAChR). The functional consequences of such binding were investigated here using the following OP compounds: VX, echothiophate, sarin, and soman. VX (charged at physiological pH) and echothiophate (formally charged) inhibited a specific signal transduction pathway in CHO...

article

Lessons from functional analysis of AChE covalent and noncovalent inhibitors for design of AD therapeutic agents

Dov Barak, Arie Ordentlich, Dana Kaplan, Chanoch Kronman, more

Chemico-Biological Interactions > 2005 > 157-158 > Complete > 219-226

Determination of the 3D-structure of acetylcholinesterase (AChE) of Torpedo californica over a decade ago, and more recently that of human enzyme together with extensive targeted mutagenesis of the mammalian AChEs led to a fine mapping of the multiple functional domains within the active center of the enzyme. Many of the contributions of this active center architecture to accommodation of noncovalent...

article

Functional requirements for the optimal catalytic configuration of the AChE active center

Avigdor Shafferman, Dov Barak, Dana Kaplan, Arie Ordentlich, more

Chemico-Biological Interactions > 2005 > 157-158 > Complete > 123-131

Functional analysis of the HuAChE active center architecture revealed that accommodation of structurally diverse substrates and other ligands is achieved through interactions with specific subsites such as the acyl pocket, cation binding site, hydrophobic site or the oxyanion hole. Recent studies have begun to unravel the role of this active center architecture in maintaining the optimal catalytic...

article

The role of AChE active site gorge in determining stereoselectivity of charged and noncharged VX enantiomers

Arie Ordentlich, Dov Barak, Gali Sod-Moriah, Dana Kaplan, more

Chemico-Biological Interactions > 2005 > 157-158 > Complete > 191-198

The reactivity of human acetylcholinesterase (HuAChE) toward the chemical warfare agent VX {O-ethyl S-[2-(diisopropylamino)ethyl] methyl-phosphonothioate} and its stereoselectivity toward the P ^S -enantiomer were investigated by examining the reactivity of HuAChE and its mutant derivatives toward purified enantiomers of VX and its noncharged isostere nc-VX [O-ethyl S-(3-isopropyl-4-methyl-pentyl)...

article

Stereoselectivity toward VX Is Determined by Interactions with Residues of the Acyl Pocket as Well as of the Peripheral Anionic Site of AChE ^†

Arie Ordentlich, Dov Barak, Gali Sod-Moriah, Dana Kaplan, more

Biochemistry > 2004 > 43 > 35 > 11255 - 11265

article

Is Aromaticity Essential for Trapping the Catalytic Histidine 447 in Human Acetylcholinesterase? ^†

Dana Kaplan, Dov Barak, Arie Ordentlich, Chanoch Kronman, more

Biochemistry > 2004 > 43 > 11 > 3129 - 3136

article

Structural Determinants of A ₃ Adenosine Receptor Activation: Nucleoside Ligands at the Agonist/Antagonist Boundary

Zhan-Guo Gao, Soo-Kyung Kim, Thibaud Biadatti, Wangzhong Chen, more

Journal of Medicinal Chemistry > 2002 > 45 > 20 > 4471 - 4484

article

The Aromatic “Trapping” of the Catalytic Histidine Is Essential for Efficient Catalysis in Acetylcholinesterase ^†

Dov Barak, Dana Kaplan, Arie Ordentlich, Naomi Ariel, more

Biochemistry > 2002 > 41 > 26 > 8245 - 8252

article

Neoceptor Concept Based on Molecular Complementarity in GPCRs: A Mutant Adenosine A ₃ Receptor with Selectively Enhanced Affinity for Amine-Modified Nucleosides

Kenneth A. Jacobson, Zhan-Guo Gao, Aishe Chen, Dov Barak, more

Journal of Medicinal Chemistry > 2001 > 44 > 24 > 4125 - 4136

article

Acyclic and Cyclopropyl Analogues of Adenosine Bisphosphate Antagonists of the P2Y ₁ Receptor: Structure−Activity Relationships and Receptor Docking

Hak Sung Kim, Dov Barak, T. Kendall Harden, José L. Boyer, more

Journal of Medicinal Chemistry > 2001 > 44 > 19 > 3092 - 3108

article

Constitutive Activation of A ₃ Adenosine Receptors by Site-Directed Mutagenesis

Aishe Chen, Zhan-Guo Gao, Dov Barak, Bruce T. Liang, more

Biochemical and Biophysical Research Communications > 2001 > 284 > 3 > 596-601

The objective of this study was to create constitutively active mutant human A ₃ adenosine receptors (ARs) using single amino acid replacements, based on findings from other G protein-coupled receptors. A ₃ ARs mutated in transmembrane helical domains (TMs) 1, 3, 6, and 7 were expressed in COS-7 cells and subjected to agonist radioligand binding and phospholipase C (PLC) and adenylyl...

article

Does “Butyrylization” of Acetylcholinesterase through Substitution of the Six Divergent Aromatic Amino Acids in the Active Center Gorge Generate an Enzyme Mimic of Butyrylcholinesterase? ^†

Dana Kaplan, Arie Ordentlich, Dov Barak, Naomi Ariel, more

Biochemistry > 2001 > 40 > 25 > 7433 - 7445

article

A preliminary comparison of structural models for catalytic intermediates of acetylcholinesterase

Israel Silman, Charles B. Millard, Arie Ordentlich, Harry M. Greenblatt, more

Chemico-Biological Interactions > 1999 > 119-120 > Complete > 43-52

Determination of the three dimensional structure of Torpedo Californica acetylcholinesterase (TcAChE) provided an experimental tool for directly visualizing interaction of AChE with cholinesterase inhibitors of fundamental, pharmacological and toxicological interest. The structure revealed that the active site is located near the bottom of a deep and narrow gorge lined with 14 conserved aromatic amino...

article

Direct determination of the chemical composition of acetylcholinesterase phosphonylation products utilizing electrospray-ionization mass spectrometry

Ruth Barak, Arie Ordentlich, Dov Barak, Meir Fischer, more

FEBS Letters > 1997 > 407 > 3 > 347-352

While non-reactivability of cholinesterases from their phosphyl conjugates (aging) is attributed to an unimolecular process involving loss of alkyl group from the phosphyl moiety, no conclusive evidence is available that this is the only reaction path and involvement of other post-inhibitory processes cannot be ruled out. To address this issue, molecular masses of the bacterially expressed recombinant...

article

Structural modifications of the Ω loop in human acetylcholinesterase

Baruch Velan, Dov Barak, Naomi Ariel, Moshe Leitner, more

FEBS Letters > 1996 > 395 > 1 > 22-28

Conformational mobility of the surface Ω loop (Cys-69-Cys-96) in human acetylcholinesterase (HuAChE) was recently implicated in substrate accessibility to the active center and in the mechanism of allosteric modulation of enzymatic activity. We therefore generated and kinetically evaluated the following modifications or replacements in HuAChE: (a) residues at the loop ends, (b) residues involved...

article

Engineering resistance to 'aging' of phosphylated human acetylcholinesterase Role of hydrogen bond network in the active center

Arie Ordentlich, Chanoch Kronman, Dov Barak, Dana Stein, more

FEBS Letters > 1993 > 334 > 2 > 215-220

Recombinant human acetylcholinesterase (HuAChE) and selected mutants (E202Q, Y337A, E450A) were studied with respect to catalytic activity towards charged and noncharged substrates, phosphylation with organophosphorus (OP) inhibitors and subsequent aging of the OP-conjugates. Amino acid E450, unlike residues E202 and Y337, is not within interaction distance from the active center. Yet, the bimolecular...

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