Human Acetyl Research Articles

In silico Analysis of Selected Four-Leaf Water Clover (Marsilea species) Constituents as Human Acetyl Cholinesterase (hAchE), Carbonic Anhydrase II (hCA-II), and Protein Tyrosine Phosphatase 1B (PTP1B) Inhibitory Agents

ABSTRACT A four-leaf water clover (Marsilea species) has been reported to exhibit various biological activities. In the present study, we aimed to evaluate 23 selected constituents of a four-leaf water clover (Marsilea species) as potent inhibitory agents of human acetyl cholinesterase (hAchE), carbonic anhydrase II (hCA-II), and protein tyrosine phosphatase 1B (hPTP-1B) using an in silico method. The 23 selected constituents of the four-leaf water clover (Marsilea species) were studied on the docking behavior of hAchE, hCA-II, and hPTP-1B by using the Webina docking method. In addition to docking, toxicity analysis was also performed using the pkCSM web server. Toxicity analysis has shown that 10 ligands (44%) of the four-leaf water clover (Marsilea species) were predicted to have hERG II (human ether-a-go-go-related gene) inhibition activity. The docking analysis showed that marsilin has exhibited the maximum binding energy (-11.3 kcal/mol) with the hAchE, whereas it fails to dock with both the target enzymes (hCA-II and hPTP-1B). Thus, the present find provides a new understanding about the 23 selected ligands of the four-leaf water clover (Marsilea species) as potent inhibitory agents of human acetyl cholinesterase (hAchE), carbonic anhydrase II (hCA-II), and protein tyrosine phosphatase 1B (hPTP-1B).

Activation/Inhibition of Cholinesterases by Excess Substrate: Interpretation of the Phenomenological b Factor in Steady-State Rate Equation

Cholinesterases (ChEs) display a non-michaelian behavior with positively charged substrates. In the steady-state rate equation, the b factor describes this behavior: if b > 1 there is substrate activation, if b < 1 there is substrate inhibition. The mechanistic significance of the b factor was investigated to determine whether this behavior depends on acylation, deacylation or on both steps. Kinetics of human acetyl- (AChE) and butyryl-cholinesterase (BChE) were performed under steady-state conditions and using a time-course of complete substrate hydrolysis. For the hydrolysis of short acyl(thio)esters, where acylation and deacylation are partly rate-limiting, steady-state kinetic analysis could not decide which step determines b. However, the study of the hydrolysis of an arylacylamide, 3-(acetamido)-N,N,N-trimethylanilinium (ATMA), where acetylation is rate-limiting, showed that b depends on the acylation step. The magnitude of b and opposite b values between AChE and BChE for the hydrolysis of acetyl(thio)- versus benzoyl-(thio) esters, then indicated that the productive adjustment of substrates in the active center at high concentration depends on motions of both the Ω and the acyl-binding loops. Benzoylcholine was shown to be a poor substrate of AChE, and steady-state kinetics showed a sudden inhibition at high concentration, likely due to the non-dissociation of hydrolysis products. The poor catalytic hydrolysis of this bulky ester by AChE illustrates the importance of the fine adjustment of substrate acyl moiety in the acyl-binding pocket. Molecular modeling and QM/MM simulations should definitively provide evidence for this statement.

Using Small Branches of Bombax ceiba Instead of Stem Bark for a Conservative Sourcing Approach: Comparative Studies of Chemical Profiling by LC‐MS, GC‐MS, and HPLC

AbstractThe purpose of the current study piece is to use short branches rather than stem bark to take a conservative approach to the Bombax ceiba plant. Similarities were found in the HPLC, LCMS, and GCMS data of the plant‘s stem bark and tiny branches. Analysis using liquid chromatography‐mass spectrometry (LC‐MS) of abundant medicinal phytochemicals of Bombax ceiba and its Molecular Docking Interaction with AKT Protein Kinase, Human Acetyl Choline Esterase, and Pancreatic Lipase Colipase Target Protein. According to the HPLC study results, Bombax ceiba stem bark contains 0.359 % lupeol, whereas tiny branches have 0.039 %. Three compounds have good binding energy (Kcal/mol) with Human acetyl choline esterase, while seven compounds have very good binding energy (Kcal/mol) with AKT Protein kinase and Pancreatic Lipase Colipase. Small branches are essentially identical to stem bark in terms of their chemical composition that makes them active against certain target proteins.

The Chemotype of Chromanones as a Privileged Scaffold for Multineurotarget Anti-Alzheimer Agents.

The multifactorial nature of Alzheimer's disease necessitates the development of agents able to interfere with different relevant targets. A series of 22 tailored chromanones was conceptualized, synthesized, and subjected to biological evaluation. We identified one representative bearing a linker-connected azepane moiety (compound 19) with balanced pharmacological properties. Compound 19 exhibited inhibitory activities against human acetyl-, butyrylcholinesterase and monoamine oxidase-B, as well as high affinity to both the σ1 and σ2 receptors. Our study provides a framework for the development of further chromanone-based multineurotarget agents.

Synthesis of Isomeric 3-Benzazecines Decorated with Endocyclic Allene Moiety and Exocyclic Conjugated Double Bond and Evaluation of Their Anticholinesterase Activity.

Transformations of 1-methoxymethylethynyl substituted isoquinolines triggered by terminal alkynes in alcohols were studied and new 3-benzazecine-containing compounds synthesized, such as 6-methoxymethyl-3-benzazecines incorporating an endocyclic C6–C8 allene fragment and the -ylidene derivatives 6-methoxymethylene-3-benzazecines. The reaction mechanisms were investigated and a preliminary in vitro screening of their potential inhibitory activities against human acetyl- and butyrylcholinesterases (AChE and BChE) and monoamine oxidases A and B (MAO-A and MAO-B) showed that the allene compounds were more potent than the corresponding -ylidene ones as selective AChE inhibitors. Among the allenes, 3e (R3 = CH2OMe) was found to be a competitive AChE inhibitor with a low micromolar inhibition constant value (Ki = 4.9 μM), equipotent with the corresponding 6-phenyl derivative 3n (R3 = Ph, Ki = 4.5 μM), but 90-fold more water-soluble.

In Silico and Ex Vivo Analyses of the Inhibitory Action of the Alzheimer Drug Posiphen and Primary Metabolites with Human Acetyl- and Butyrylcholinesterase Enzymes.

Alzheimer’s disease (AD) is the most common neurodegenerative disorder worldwide. Ongoing research to develop AD treatments has characterized multiple drug targets including the cholinergic system, amyloid-β peptide, phosphorylated tau, and neuroinflammation. These systems have the potential to interact to either drive or slow AD progression. Promising agents that simultaneously impact many of these drug targets are the AD experimental drug Posiphen and its enantiomer phenserine that, currently, are separately being evaluated in clinical trials. To define the cholinergic component of these agents, the anticholinesterase activities of a ligand dataset comprising Posiphen and primary metabolites ((+)-N1-norPosiphen, (+)-N8-norPosiphen, and (+)-N1,N8-bisnorPosiphen) were characterized and compared to those of the enantiomer phenserine. The “target” dataset involved the human cholinesterase enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Binding interactions between the ligands and targets were analyzed using Autodock 4.2. The computationally determined inhibitory action of these ligands was then compared to ex vivo laboratory-measured values versus human AChE and BChE. While Posiphen lacked AChE inhibitory action, its major and minor metabolites (+)-N1-norPosiphen and (+)-N1,N8-bisnorPosiphen, respectively, possessed modest AChE inhibitory activity, and Posiphen and all metabolites lacked BChE action. Phenserine, as a positive control, demonstrated AChE-selective inhibitory action. In light of AChE inhibitory action deriving from a major and minor Posiphen metabolite, current Posiphen clinical trials in AD and related disorders should additionally evaluate AChE inhibition; particularly if Posiphen should be combined with a known anticholinesterase, since this drug class is clinically approved and the standard of care for AD subjects, and excessive AChE inhibition may impact drug tolerability.

Modulatory effect of opioid administration on the activity of cholinesterase enzyme: a systematic review of mice/rat models

We aimed to review the literature to find the specific effect of opioids on the activity of cholinesterase (ChE) enzyme which plays a substantial role in the functioning of cholinergic system. Literature search was performed by two independent reviewers in order to find relevant articles about the changes in the activity of ChE in mice or rat following opioid administration. Based on findings from literature review, opioid administration is able to induce cholinergic modulation via decreasing or increasing the activity of ChE enzyme. However, the degree of variation of ChE in various brain regions is different. No gender differences was reported in the effect of opioids on ChE activity. Although chronic opioid administration may decrease enzyme function, ChE activity might be unchanged following opioid withdrawal using naloxone or the development of tolerance. Opioid type affects whether or not naloxone can reverse the changes of ChE. Direct inhibitory action of morphine and the other opioid ligands believed responsible for the decrease in the ChE activity. Moreover, the potency of codeine to induce allosteric enhancement of acetylcholine receptor signaling might be involved in the cholinergic modulation of codeine and other opioids. Animal studies on rat and mice showed that opioids may change the activity of ChE. These changes can pertain an increase or decrease in enzyme activity; as there might be no change. The type of opioid used may have an effect on the cholinergic modulation. It is beneficial to conduct cross-sectional and cohort studies on addicted individuals, especially opium abusers, to find the precise association of opioids with alterations in human acetyl cholinesterase or butyrylcholinesterase. Simulation studies can also examine the structure-function relationships and provide important details to better understand the mechanism of action of opioid compounds on ChE activity. In addition, understanding how opioids impact ChE activity may help perform proper interventions for drug abstinence.

Highlights of ASS234: a novel and promising therapeutic agent for Alzheimer's disease therapy.

There is no effective treatment to face Alzheimer’s disease complexity. Multitarget molecules are a good approach against the multiple physiopathological events associated with its development and progression. In this context, N-((5-(3-(1-benzylpiperidin-4-yl) propoxy)-1- methyl-1H-indol-2-yl)methyl)-N-methylprop-2-yn-1-amine (ASS234) has been tested achieving promising results. ASS234 has demonstrated to cross the blood-brain barrier in vivo, and a good in silico safety profile being less toxic than donepezil. Besides, ASS234 reversibly inhibits human acetyl- and butyryl-cholinesterase, and irreversibly inhibits human monoamine oxidase A and B. Moreover, this multitarget molecule has antioxidant and neuroprotective properties, and inhibits Αβ1–42 and Αβ1–40 self-aggregation. Inquiring about the mechanism of action, several signaling pathways related to Alzheimer’s disease had been explored showing that ASS234 induces the wingless-type MMTV integration site (Wnt) family and several members of the heat shock proteins family and moreover counteracts neuroinflammatory and oxidative stress-related genes promoting the induction of several key antioxidant genes. Finally, in vivo experiments with ASS234 in C57BL/6J mice displayed its ability to reduce amyloid plaque burden and gliosis in the cortex and hippocampus, ameliorating scopolamine-induced learning deficits. Here we gather the information regarding ASS234 evaluated so far, showing its ability to face different targets, necessary to counteract a neurodegenerative disease as complex as the Alzheimer’s disease.

Humans and Chimpanzees Display Opposite Patterns of Diversity in Arylamine N-Acetyltransferase Genes.

Among the many genes involved in the metabolism of therapeutic drugs, human arylamine N-acetyltransferases (NATs) genes have been extensively studied, due to their medical importance both in pharmacogenetics and disease epidemiology. One member of this small gene family, NAT2, is established as the locus of the classic human acetylation polymorphism in drug metabolism. Current hypotheses hold that selective processes favoring haplotypes conferring lower NAT2 activity have been operating in modern humans’ recent history as an adaptation to local chemical and dietary environments. To shed new light on such hypotheses, we investigated the genetic diversity of the three members of the NAT gene family in seven hominid species, including modern humans, Neanderthals and Denisovans. Little polymorphism sharing was found among hominids, yet all species displayed high NAT diversity, but distributed in an opposite fashion in chimpanzees and bonobos (Pan genus) compared to modern humans, with higher diversity in Pan species at NAT1 and lower at NAT2, while the reverse is observed in humans. This pattern was also reflected in the results returned by selective neutrality tests, which suggest, in agreement with the predicted functional impact of mutations detected in non-human primates, stronger directional selection, presumably purifying selection, at NAT1 in modern humans, and at NAT2 in chimpanzees. Overall, the results point to the evolution of divergent functions of these highly homologous genes in the different primate species, possibly related to their specific chemical/dietary environment (exposome) and we hypothesize that this is likely linked to the emergence of controlled fire use in the human lineage.

Analysis and prediction of human acetylation using a cascade classifier based on support vector machine

BackgroundAcetylation on lysine is a widespread post-translational modification which is reversible and plays a crucial role in some biological activities. To better understand the mechanism, it is necessary to identify acetylation sites in proteins accurately. Computational methods are popular because they are more convenient and faster than experimental methods. In this study, we proposed a new computational method to predict acetylation sites in human by combining sequence features and structural features including physicochemical property (PCP), position specific score matrix (PSSM), auto covariation (AC), residue composition (RC), secondary structure (SS) and accessible surface area (ASA), which can well characterize the information of acetylated lysine sites. Besides, a two-step feature selection was applied, which combined mRMR and IFS. It finally trained a cascade classifier based on SVM, which successfully solved the imbalance between positive samples and negative samples and covered all negative sample information.ResultsThe performance of this method is measured with a specificity of 72.19% and a sensibility of 76.71% on independent dataset which shows that a cascade SVM classifier outperforms single SVM classifier.ConclusionsIn addition to the analysis of experimental results, we also made a systematic and comprehensive analysis of the acetylation data.

Analysis of human acetylation stoichiometry defines mechanistic constraints on protein regulation

Lysine acetylation is a reversible posttranslational modification that occurs at thousands of sites on human proteins. However, the stoichiometry of acetylation remains poorly characterized, and is important for understanding acetylation-dependent mechanisms of protein regulation. Here we provide accurate, validated measurements of acetylation stoichiometry at 6829 sites on 2535 proteins in human cervical cancer (HeLa) cells. Most acetylation occurs at very low stoichiometry (median 0.02%), whereas high stoichiometry acetylation (>1%) occurs on nuclear proteins involved in gene transcription and on acetyltransferases. Analysis of acetylation copy numbers show that histones harbor the majority of acetylated lysine residues in human cells. Class I deacetylases target a greater proportion of high stoichiometry acetylation compared to SIRT1 and HDAC6. The acetyltransferases CBP and p300 catalyze a majority (65%) of high stoichiometry acetylation. This resource dataset provides valuable information for evaluating the impact of individual acetylation sites on protein function and for building accurate mechanistic models.

Structural Characterization of i-Motif Structure in the Human Acetyl-CoA Carboxylase 1 Gene Promoters and Their Role in the Regulation of Gene Expression.

The polypurine/polypyrimidine-rich sequences within the promoters (PI and PII) of human acetyl coenzyme A (CoA) carboxylase 1 (ACC1) gene play a vital role in determining hormone- or diet-inducible expression of ACC1. PI and PII contain consecutive runs of three and three to five G/C base pairs, respectively. In a previous study, G-rich DNA sequences of human ACC1 PI and PII were found to fold into G-quadruplex structures; these consequently acted as strong barriers to transcription and DNA replication. Typically, stretches of C-rich sequences that coexist with stretches of guanines have the capacity to form another four-stranded secondary structure known as an i-motif. However, studies on the i-motif structure are limited and its functional significance is unclear. In the current study, through the use of a combination of different techniques, it is demonstrated that C-rich single-stranded DNA derived from ACC1 PI and PII form intramolecular i-motif structures and affect normal DNA metabolic processes. Additionally, the C-rich strands of PI and PII in duplex DNA adopt the i-motif conformation in crowded solution environments at neutral pH. Notably, the i-motif-forming sequences of PI and PII suppressed luciferase gene transcription in HeLa cells. Furthermore, substitution of a nucleotide sequence that has no potential to form the i-motif structure increases luciferase gene expression in HeLa cells. These results support the idea that C-rich sequences within ACC1 PI and PII can form intramolecular i-motif structures, cause suppression of transcription, and thus reveal the functional significance of C-rich sequences in the regulation of ACC1 gene expression.

Antitumor/Antifungal Celecoxib Derivative AR-12 is a Non-Nucleoside Inhibitor of the ANL-Family Adenylating Enzyme Acetyl CoA Synthetase.

AR-12/OSU-03012 is an antitumor celecoxib-derivative that has progressed to Phase I clinical trial as an anticancer agent and has activity against a number of infectious agents including fungi, bacteria and viruses. However, the mechanism of these activities has remained unclear. Based on a chemical-genetic profiling approach in yeast, we have found that AR-12 is an ATP-competitive, time-dependent inhibitor of yeast acetyl coenzyme A synthetase. AR-12-treated fungal cells show phenotypes consistent with the genetic reduction of acetyl CoA synthetase activity, including induction of autophagy, decreased histone acetylation, and loss of cellular integrity. In addition, AR-12 is a weak inhibitor of human acetyl CoA synthetase ACCS2. Acetyl CoA synthetase activity is essential in many fungi and parasites. In contrast, acetyl CoA is primarily synthesized by an alternate enzyme, ATP-citrate lyase, in mammalian cells. Taken together, our results indicate that AR-12 is a non-nucleoside acetyl CoA synthetase inhibitor and that acetyl CoA synthetase may be a feasible antifungal drug target.

Cellular Transplantation as the Treatment of Alzheimer’s Diseas e in Mouse Models

Acetylcholine (Ach) and N-methyl-D-aspartate (NMDA) have been two major therapeutic targets of Alzheimer’s disease (AD) for decade. However, truly effective remedy for AD has not been successfully developed. We previously transplanted neurons derived from human induced pluripotent stem (hiPS) cells into the hippocampus of human amyloid precursor protein transgenic AD model mice. The cell transplantation significantly improved cognitive dysfunction in the dementia model mice. Human choline acetyl transferase (ChAT) positive cholinergic neurons located throughout the cortex of the grafted mice. Human and mouse ChAT positive neurons and alpha7 nicotinic acetylcholine receptor (α7nAChR) positive neurons significantly increased in the cortex and hippocampus of the grafted dementia mice compared with the vehicle injected dementia mice. Human and mouse vesicular GABA transporter (VGAT) positive neurons distributed mainly in the hippocampus and, though the number was small, human VGAT positive neurons located in the cortex. In the grafted mouse cortex, the number of GABA receptor (GABAR) positive neurons of both hiPS origin and mouse origin increased significantly compared with those in the vehicle injected mouse cortex. We suggested that positive feedback loops of neurotransmitter secretion of the cortex and hippocampus induced the characteristic distribution of the transplanted neurons. In this review, we summarized current advances in stem cell therapy for dementia model mice, especially to highlight the relationships between major neurotransmitters and host/transplanted neurons.

Abstract 16449: miR-195 Regulates Myocardial SIRT3 Expression and Mitochondrial Enzyme Acetylation

Background: Unique cardiac and systemic miRNAs play an important role in cardiac remodeling and the associated response to injury by modulating key signaling elements. Through deep-sequencing of cardiac and circulating non-coding miRNAs, we identified miR-195 as the only miRNA up-regulated in plasma, serum and myocardium of patients with advanced heart failure (HF). Further, binding elements for miR-195 were found in the 3’UTR region of sirtuin3 (SIRT3), the major mitochondrial deacetylase. We hypothesized that miR-195 regulates myocardial SIRT3 expression and mitochondrial protein acetylation levels with subsequent changes in cardiac metabolism. Methods: Cellular signaling was analyzed in human cardiomyocyte-like AC16 cells and acetylation levels in a rodent model of transgenic miR-195 overexpression were compared to WT. Luciferase assays, Western blotting and immunoprecipitation (Co-IP) assays were performed. Enzymatic activities of pyruvate dehydrogenase (PDH) and ATP synthase were measured. Results: We observed suppression of SIRT3 and increased total protein acetylation in failing human myocardium. Luciferase assays confirmed that miR-195 directly targets the SIRT3 mRNA 3’UTR and negatively regulates SIRT3 expression. Transfection of miR-195 into AC16 cells resulted in a pronounced decrease in SIRT3 expression levels and induction of total protein acetylation levels. Myocardium of miR-195 transgenic animals was showed a global increase in total protein acetylation compared to WT. Co-IP assays revealed increased acetylation of 3 subunits of PDH (2.1-, 1.6-, 2.2-fold) and ATP synthase α subunit (2.3-fold), two key regulators of mitochondrial energy metabolism. Enhanced acetylation of these proteins correlated with a 24% decrease in PDH activity and a 30% decrease in ATP synthase activity. Conclusions: Altogether, these data demonstrate a crucial role of miR-195 in HF and identified SIRT3 as a direct target of miR-195. Our findings suggest a new pathway of abnormal cardiac energy metabolism in the failing myocardium through miR-195-mediated SIRT3 suppression and increased protein acetylation. These changes result in specific inhibition of PDH and ATP synthase activity leading to impaired energy metabolism and ATP deprivation.

HDAC1 is a novel regulator of nitric oxide synthase 3 in endothelial cells (860.3)

Recent studies have identified that acetylation of lysines on NOS3 regulates NO production; however, there is little information regarding deacetylation of NOS3. Histone deacetylases (HDACs) remove acetyl groups from histone and non‐histone proteins. Recently it was reported that HDAC3 antagonizes aspirin‐induced NOS3 acetylation and reduces NO production in HUVECs. The role of other HDAC isoforms in mediating NOS3 deacetylation and/or NO production has not been determined. We tested the hypothesis that HDAC1 interacts with NOS3 leading to a decrease in lysine acetylation and NO production. Bovine Aortic Endothelial Cells (BAECs) were transfected with empty vector (N = 6) or human HDAC1 (N = 6) and lysine acetylation and NO production determined. In BAECs, we found that HDAC1 and NOS3 interact, and cells over‐expressing (OE) HDAC1 expressed reduced NOS3 acetylation (vector control = 1.0 ± 0.04, OE HDAC1 = 0.6 ± 0.04 A.U.; P < 0.001). We observed no differences in NOS3 phosphorylation at T495, S633, or S1177. Basal nitrite production was also reduced in the OE HDAC1 cells (356 ± 15 pmol/mg prt/h vs 223 ± 35 pmol/mg prt/h; P < 0.05). Stimulation of BAECs by 100 nM endothelin‐1 resulted in blunted nitrite production in OE HDAC1 cells (607± 115 pmol/mg prt/h vs 321 ± 61 pmol/mg prt/h; P < 0.05). In conclusion, HDAC1 is a novel inhibitor of NOS3 acetylation and NO production.Grant Funding Source: Supported by NIH to JSP

Kinetic and structural analysis of the irreversible inhibition of human monoamine oxidases by ASS234, a multi-target compound designed for use in Alzheimer's disease

Monoamine oxidases (MAO) and cholinesterases are validated targets in the design of drugs for the treatment of Alzheimer's disease. The multi-target compound N-((5-(3-(1-benzylpiperidin-4-yl)propoxy)-1-methyl-1H-indol-2-yl)methyl)-N-methylprop-2-yn-1-amine (ASS234), bearing the MAO-inhibiting propargyl group attached to a donepezil moiety that inhibits cholinesterases, retained activity against human acetyl- and butyryl-cholinesterases. The inhibition of MAO A and MAO B by ASS234 was characterized and compared to other known MAO inhibitors. ASS234 was almost as effective as clorgyline (kinact/KI=3×106 min−1M−1) and was shown by structural studies to form the same N5 covalent adduct with the FAD cofactor.

Tryptoline-3-hydroxypyridinaldoxime conjugates as efficient reactivators of phosphylated human acetyl and butyrylcholinesterases

Two promising uncharged reactivators for inhibited human BChE and AChE have been described. These compounds show an ability to reactivate VX-inhibited BChE largely superior to those of known pyridinium aldoximes. Moreover, these oximes also exhibit a good ability to reactivate VX-, tabun- and paraoxon-inhibited human AChE.

Molecular modelling studies on flavonoid derivatives as dual site inhibitors of human acetyl cholinesterase using 3D-QSAR, pharmacophore and high throughput screening approaches

Alzheimer’s disease (AD) is a multi-factorial neurodegenerative disease that affects millions of elderly people worldwide. Due to its massive occurrence and severity, there is continuing and compelling need for the development of novel and effective drugs for improved treatment of AD. Since AD is characterized by the deficiency in cholinergic neurotransmission, acetyl cholinesterase (AChE) has been considered as a promising drug target. Herein we triggered our effort to design novel and potential inhibitors of AChE using a set of 24 flavonoid compounds having inhibitory activity against AChE. We carried out 3D-QSAR-based and pharmacophore-based identification of novel natural lead candidates. The 3D-QSAR model obtained using partial least square regression showed satisfactory parametric values (r2 = 0.8227, q2 = 0.6833 and pred-r2 = 0.7893). Amongst total 14 pharmacophore hypothesis generated the one possessing following five features: one hydrogen bond acceptor, two hydrophobic regions and two aromatic rings, was considered to be the best pharmacophore hypothesis. Above-described robust and validated 3D-QSAR and pharmacophore models were used for carrying out prospective generic prediction and virtual screening on large natural compound libraries. The screened molecules from both the approaches were subjected for further docking analysis to reveal the binding modes of actions of these ligands. All the ligands were found to bind with both catalytic and anionic subsite of AChE. The molecular insights obtained from this study will be of high value for design and development of novel drugs for AD, possessing improved binding properties and low toxicity to human.

An acetylome peptide microarray reveals specificities and deacetylation substrates for all human sirtuin isoforms

Sirtuin enzymes regulate metabolism and aging processes through deacetylation of acetyl-lysines in target proteins. More than 6,800 mammalian acetylation sites are known, but few targets have been assigned to most sirtuin isoforms, hampering our understanding of sirtuin function. Here we describe a peptide microarray system displaying 6,802 human acetylation sites for the parallel characterisation of their modification by deacetylases. Deacetylation data for all seven human sirtuins obtained with this system reveal isoform-specific substrate preferences and deacetylation substrate candidates for all sirtuin isoforms, including Sirt4. We confirm malate dehydrogenase protein as a Sirt3 substrate and show that peroxiredoxin 1 and high-mobility group B1 protein are deacetylated by Sirt5 and Sirt1, respectively, at the identified sites, rendering them likely new in vivo substrates. Our microarray platform enables parallel studies on physiological acetylation sites and the deacetylation data presented provide an exciting resource for the identification of novel substrates for all human sirtuins.