Melanocytes are pigment-producing cells that colour our hair, skin and eyes. Melanocytes are evolutionary conserved in vertebrates, and in addition to contributing to pigmentation and pattern formation, can contribute to background adaptation (zebrafish) and protection against harmful UV irradiation (humans). Many of the processes involved in melanocyte development – such as migration, proliferation and differentiation - are misregulated in melanoma. Here, I use chemical biology in zebrafish to identify targetable pathways in melanocyte development and regeneration, with a view to how these processes may be misregulated in melanoma and other pigmentation syndromes. We first wanted to address the potential for small molecules to regulate multiple stages of melanocyte development and differentiation. In Chapter 3, I describe my work involved in a small molecule screen for clinically active compounds that alter melanocyte biology (Colanesi et al., 2012). In this work we have identified small-molecules that affect melanocyte migration, differentiation, survival, morphology and number. This is important as it highlights new pathways essential for normal melanocyte development and consequently provides further tools in which to study melanocytes. Identifying the target of small molecules in vivo is a challenge in chemical biology. In Chapter 4, I describe my contributions to understanding how 5-nitrofuran compounds act in zebrafish (Zhou et al., 2012). My work has contributed to understanding the activity of 5-nitrofurans is dependent upon its nitrofuran ring structure. I have also helped confirm a conserved interaction between 5-nitrofurans and ALDH2, which may contribute to the off-target effects observed in the clinic. These results are important as they aid further understand of the 5-nitrofuran class of drugs and give evidence to support combination therapy of 5-nitrofurans with ALDH2 inhibitors as a way to overcome clinical side effects. Additionally I show that NFN1 treatment limits ensuing melanocyte regeneration thereby suggesting a role at the Melanocyte Stem Cell (MSC), which provides me with a key tool to study melanocyte regeneration in zebrafish. How tissue specific cell numbers are specified and maintained is a key question in developmental biology. In Chapter 5, I describe the identification of the MITF gene in the maintenance of cell cycle arrest in differentiated melanocytes (Taylor et al., 2011). We show that the human melanoma mutation MITF4TΔ2B promotes melanocyte division, thereby suggesting a role for melanocyte division in the pathogenesis of melanoma. This work is valuable because it highlights Mitf as a molecular rheostat that controls melanocyte proliferation and differentiation in living vertebrates, and helps us to understand the role of MITF in melanoma progression. Little is known about the pathways that control melanocyte stem cells in animals. To identify new melanocyte stem cell pathways, I used NFN1 as the basis for a small molecule screen for enhancers of melanocyte regeneration (Chapter 6). I find that chemical inhibition of Phosphatase of Regenerating Liver-3 (Prl-3) in zebrafish can enhance melanocyte regeneration. Importantly, I have found that there are an increased number of melanocyte progenitor cells in PRL3-inhibitor treated zebrafish. I propose that PRL-3 may control progenitor cell number in melanocyte regeneration. This is significant because it identifies PRL-3 as a novel molecular target controlling melanocyte progenitor cells, and identifies a new chemical tool with which to study melanocyte differentiation from a progenitor population. In the final chapter, I discuss how this work relates to the larger field of melanocyte developmental biology, and the new insight it provides into the fundamental processes of how organisms control cell number and pattern formation. In addition, I discuss how this work may have implications for understanding and treating melanocyte diseases, such as vitiligo (loss of melanocytes) and melanoma (cancer of the melanocyte).

The focus of this thesis is the synthesis of organometallic complexes incorporating the η8-permethylpentalene titanium moiety (η⁸-Pn*Ti), their characterisation, and their reactivity with small molecules. <b>Chapter One</b> summarises the chemistry of the pentalene molecule, from its instability in the free state to the incorporation of the hydrocarbon into organometallic complexes. The chapter continues with a review of the coordination modes available to Pn and concludes with a brief discussion on the effects of permethylation of hydrocarbon ligands and the advent of permethylpentalene (Pn*). <b>Chapter Two</b> documents the improved synthesis of [Pn*TiCl(μ-Cl)]₂ utilising isomeric control imparted on the Pn* synthon, Pn*(SnMe₃)₂. This protocol permits access to a variety of methylated compounds through metathesis chemistry, of which five have been crystallographically elucidated, revealing the fold angle to be reliant on an interplay between steric and electronic factors. Mono-, bi- and trimetallic {Pn*TiMe₂, [Pn*TiMe(μ-Cl)]₂ and [Pn*Ti(μ-Me)]₂(μ-CH₂), and [Pn*TiMe(μ-Me)₂]₂Mg respectively} species were synthesised dependent on the methylating agent employed and they displayed varying thermal stabilities, with the dimeric nature of [Pn*TiMe(μ-Cl)]₂ proving crucial in the formation of [Pn*Ti(μ-Cl)]₂(μ-CH₂). <b>Chapter Three</b> describes the incorporation of classical organometallic ligands into the Pn*Ti moiety, including the first examples of benzyl, alkyl, aryl, allyl and η¹-Cp bound to a PnTi fragment. Seven complexes have been structurally characterised including the first ever crystal structure of a π-hydrocarbon bound Ti species bearing two CH₂^tBu groups, Pn*Ti(CH₂^tBu)₂, and the fluxional mixed hapticity complex Pn*Ti(η⁵-Cp)(η¹-Cp), whose η¹-Cp rearranges via a 1,2-sigmatropic shift. <b>Chapter Four</b> investigates the reactivity of the monomeric dialkyls, Pn*TiR₂ (R = Me, CH₂Ph, CH₂SiMe₃ and CH₂^tBu) with CO₂, CO and H₂. All four compounds demonstrate “normal” insertion of the CO₂ moiety into both Ti-R bonds, revealing a symmetrical bidentate coordination of the RCO₂ units. Computational studies have highlighted two competing pathways for their reaction with CO, dependent on the concentration of CO and size of R, which results either in formation of an enediolate or a titanoxirane. The reaction with H₂ yields the fascinating trimeric mixed valence, [Pn*Ti(μ₂-H)]₃(μ₃-H), the first structurally characterised example of a trimeric Ti-H species and the first to include a Ti-(μ₃-H) moiety. (Pn*TiCl)₂(μ-O) is formed by the action of adventitious H₂O and possesses a linear Ti-O-Ti bridge with a degree of Ti-O double bond character, supported by crystallographic data and DFT calculations. <b>Chapter Five</b> discusses ethylene polymerisation studies on the monomeric dialkyl complexes Pn*TiR₂ (R = Me, CH₂Ph, CH₂SiMe₃ and CH₂^tBu) using the activators [Ph₃C][B(C₆F₅)₄], [PhNMe₂H][B(C₆F₅)₄], AlⁱBu₃ and H₂. <b>Chapter Six</b> presents full experimental procedures for all of the syntheses and reactions outlined in Chapters Two to Five. <b>Chapter Seven</b> details characterising data for all novel compounds, and crystallographic data in the form of CIF files may be found in the electronic version.

Os tutoriais Estrutura e Estabilidade do DNA e Estabilidade do DNA são produtos da metodologia proposta neste trabalho para o desenvolvimento de tutorias de moléculas com animações interativas 3D, a qual estabelece as cinco diretrizes: i. Selecionar conteúdo de Bioquímica, Biologia molecular e Química; ii. Definir a distribuição do conteúdo e a estrutura do tutorial; iii. Integrar textos, diagramas, tabelas e animações moleculares 3D; iv. Desenvolver as animações integrando diferentes modos de representação 3D; e v. Exibir simultaneamente na página web animação molecular 3D associada com texto, diagrama ou tabela. A metodologia é fundamentada em Princípios de Aprendizagem por Multimídia de Mayer, no intuito de favorecer a aprendizagem da molécula, o que exige mais do que a mera exposição da estrutura molecular em três dimensões, sendo necessária a articulação da estrutura com mídias acessórias (3ª diretriz) para conduzir a exploração guiada e paulatina da molécula. No caso de biopolímeros, como o DNA, o aumento da complexidade estrutural torna mais necessário guiar o aprendiz pela exploração da molécula, sendo preciso explicar as interações químicas entre os monômeros e entre os monômeros com o meio aquoso para que o aprendiz compreenda a estrutura e estabeleça relações desta com as atividades biológicas do DNA. Assim, um dos princípios da metodologia é o estabelecimento de unidades conceituais que exploram gradativamente o biopolímero por meio de um texto constituído por pergunta e resposta e, em seguida, uma animação acionada pelo botão Visualize 3D. A estratégia de apresentar o conteúdo de forma segmentadaobjetiva favorecer o estabelecimento de conexões entre o conhecimento novo, apresentado na unidade conceitual, e os conceitos preexistentes do aprendiz. O texto de cada unidade possui uma organização hierárquica: i. Resposta resumida para a pergunta; ii. detalhamento da resposta; iii. estabelecimento de relação estrutura/atividade biológica. Além disso, existem hiperlinks para explicação adicional sobre conceitos químicos e bioquímico, tais como ligação de hidrogênio, fendas do DNA, etc. Também foram adotados princípios educacionais para a criação das animações. Os recursos utilizados para construção dos tutoriais foram ferramentas do Laboratório Integrado de Química e Bioquímica e estruturas moleculares obtidas do RCSB Protein Data Bank. Para avaliação do potencial instrucional dos tutoriais foram realizadas atividades com alunos de pós-graduação e graduação que responderam a um questionário antes e outro após usar os tutoriais. Também foram conduzidas entrevistas com alunos de graduação no intuito de averiguar a percepção destes sobre a metodologia de desenvolvimento de tutoriais e a aprendizagem com o uso de tutoriais de moléculas. A análise dos questionários evidenciou uma melhoria no desempenho dos estudantes após usar os tutoriais, além de eles considerarem que aprenderam e que gostariam de usar mais tutoriais de moléculas como ferramenta de ensino e aprendizagem, o que é um indicativo do potencial da metodologia proposta neste trabalho. / The \"DNA Structure and Stability\" and \"DNA Stability\" tutorials are products of the methodology proposed in this work for the development of molecular tutorials with 3D interactive animations, which establishes the five guidelines: i. Select contents of Biochemistry, Molecular Biology and Chemistry; ii. Define the content distribution and the structure of the tutorial; iii. Integrate texts, diagrams, tables and 3D molecular animations; iv. Develop the animations integrating different modes of 3D representation; and v. Simultaneously display on the web page 3D molecular animation associated with text, diagram or table. The methodology is based on Mayer\'s Multimedia Learning Principles, in order to favor the learning of the molecule, which requires more than the mere exposition of the molecular structure in three dimensions, being necessary the articulation of the structure with accessory medias (3rd guideline) to conduct the guided and gradual exploration of the molecule. In the case of biopolymers, such as DNA, increasing structural complexity makes it more necessary to guide the learner through the exploration of the molecule. It is necessary to explain the chemical interactions between the monomers and between the monomers with the aqueous medium so that the learner understands the structure and establish relations between this and the DNA biological activities. Thus, one of the principles of the methodology is the establishment of conceptual units that gradually explore the biopolymer through a text consisting of question and answer and then an animation triggered by the button \"Visualize 3D\". The strategy of presenting content in a segmented way aims to favor the establishment of connections between the new knowledge presented in the conceptual unit and thepreexisting ones in the cognitive structure of the learner. The text of each unit has a hierarchical organization: i. Brief answer to the question; ii. detailing the response; iii. establishment of the relation between structure and biological activity. In addition, there are hyperlinks for further explanation about chemical and biochemical concepts, such as hydrogen bonding, DNA grooves, etc. Educational principles were also adopted for the creation of animations. The resources used to construct the tutorials were tools of the Integrated Laboratory of Chemistry and Biochemistry and the molecular structures obtained from the RCSB Protein Data Bank. In order to evaluate the instructional potential of the tutorials, activities were carried out with undergraduate and graduate students who answered a questionnaire before and after using the tutorials. We also conducted interviews with undergraduate students in order to ascertain their perception about the methodology of developing tutorials and the learning with the use of molecular tutorials. The analysis of the questionnaires evidenced an improvement in students\' performance after using the tutorials, in addition they also consider that have learned and would like to use more molecular tutorials as a teaching and learning tool, which is an indicative of the potential of the methodology proposed in this work.

Thesis advisor: James P. Morken / Platinum-catalyzed enantioselective diboration of various hydrocarbon starting materials to form stereodefined carbon-boron bonds is reported. The asymmetric Pt-catalyzed 1,4-diboration of <italic>trans</italic>-1,3-dienes provided 1,4-bis(boronate)esters in up to 98:2 er, representing the first enantioselective diene diboration. The enantioselective 1,2-diboration of <italic>cis</italic>-1,3-dienes and 4,4-disubstituted dienes afforded 1,2-bis(boronate)esters in up to 98:2 er. The intermediate allylboronates were utilized in aldehyde allylations to furnish polypropionate-like compounds and stereodefined carbon quaternary centers. The development of a Pt-catalyzed enantioselective diboration of terminal olefins is disclosed, giving the corresponding 1,2-diols in up to 97:3 er. Further optimization and expansion of the scope of this method is also discussed. / Thesis (PhD) — Boston College, 2011. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

O uso de agrotóxicos e a consequente contaminação têm sido motivo de constante preocupação, sendo necessário monitorar esses compostos por metodologias que as quantifiquem em água e alimentos. As técnicas cromatográficas são as mais utilizadas para a este tipo de análise, mas apresentam desvantagens para aplicações \"in situ\" ou em tempo real. As técnicas eletroquímicas, como os biossensores enzimáticos que utilizam a acetilcolinesterase, têm sido estudadas para a determinação quantitativa de pesticidas em diferentes amostras. No entanto, as enzimas apresentam algumas desvantagens relacionadas com sua capacidade de desnaturação e com a inibição por outras espécies. Diante disso, foi proposta neste projeto a síntese de uma molécula mimética [ácido (4-(1E)-etanohidrazonoil) benzóico] para a acetilcolinesterase para catalisar a hidrólise do substrato (acetiltiocolina). A molécula mimética foi caracterizada por RMN e FTIR. Os produtos da reação, acetato e tiocolina, foram identificados pelo método de Ellman e FTIR. A cinética química do processo catalítico foi estudada, verificando-se que a reação era de primeira ordem em relação à concentração de acetiltiocolina e a constante de velocidade foi 0,623 s-1. Os dados experimentais obtidos com a molécula artificial foram aplicados ao modelo cinético de Michaelis-Menten e os parâmetros cinéticos foram determinados, constatando que a constante de velocidade calculada foi 13000 vezes menor que aquela calculada pelo método diferencial, o que mostrou a inconveniência de aplicar tal modelo enzimático aos catalisadores sintéticos. Além disso, verificou-se que o KM é uma constante que não possui significado quando aplicada às moléculas miméticas. / The application of pesticides and the resulting contamination have been a matter of constant concern, being necessary to monitor these compounds by methods that are able to quantify these compounds in water and food. The chromatographic techniques are most often used for this kind of analysis, but present some drawbacks for \"in situ\" or in real time applications. Electrochemical techniques, like biosensors based on the inhibition of acetylcholinesterase, have been studied for the quantitative determination of pesticides in different samples. However, the use of enzymes is complicated due to their ability to denaturation and the possible inhibition by other species. Therefore, in this project the synthesis of [4-(1E)etanehydrazonoylbenzoic acid], a mimetic molecule for acetylcholinesterase, was carried out, aiming the catalysis of acetylcholine hydrolysis. The mimetic molecule was characterized by NMR and FTIR. The products of reaction, such as acetate and thiocholine, were identified by Ellman\'s method and FTIR. The chemical kinetic of the catalytic process was characterized as of first order with respect to the acetylthiocholine concentration with a rate constant of 0.623 s-1. The experimental data obtained with the artificial molecule were applied to the Michaelis-Menten\'s model and the kinetic parameters were determined, noting that the rate constant was calculated as 13000 times smaller than that obtained by the differential method, which indicates the inconvenience of using the enzymatic model to the mimetic catalysts. Moreover, it was found that KM has no meaning when applied to mimetic molecules.

PTEN (phosphatase and tensin homolog deleted on chromosome ten) is a potent tumor suppressor. PTEN’s tumor suppressor action is rooted in its phosphatase function on the lipid substrate phosphatidylinositol-(3,4,5)-trisphosphate (PI(3,4,5)P3). PTEN’s enzymatic activity is specific for the third position of the inositol headgroup. PI(3,4,5)P3 is a second messenger that is a part of the PI3K-Akt pathway, and its dysregulation leads to constitutively activated AKT. The result of AKT activation is cell cycle progression, motility, cell growth, and proliferation, and consequently, overaction leads to neoplastic growth and tumorigenesis. PTEN antagonizes this pathway by regulating PI(3,4,5)P3 population through its phosphatase activity which produces the lipid PI(4,5)P2 (phosphatidylinositol-(4,5)-bisphosphate). A result of PTEN’s function is that its activity must be localized at the PM (plasma membrane) since this is where its substrate resides. Additionally, the mole percent of the phosphoinositide family of lipids is small. From highest percent composition to lowest the phosphoinositide species in the PM rank as PI(4,5)P2 (~2%), PI(4)P (~1%), and PI(3,4,5)P3 (~0.02%). For PTEN to turn over its substrate, it must first translocate from the cytosol to the PM and then search through the plasma membrane for this rare but high in demand lipid. This is at the center of the scarcity paradox. This work explores how PTEN may overcome this paradox by using its multiple lipid binding domains to interact with multiple lipid partners to efficiently localize it toward a region with a high probability of having PI(3,4,5)P3. This hypothesis is tested using two kinetic methodologies. First, we use pre- steady state stopped-flow spectrometry to determine the rates that govern PTEN-lipid binding. Second, we use single-molecule total internal reflectance fluorescence (smTIRF) microscopy to resolve the diffusion coefficients and dwell times of bound PTEN on SLBs supported lipid bilayers (SLBs). We test PTEN against various lipid compositions to determine how the bilayer structure in addition to the chemistry of the lipid influences the enzyme’s binding. These compositions include PI(4,5)P2, PI phosphatidylinositol (PI), phosphatidylserine (PS), PI(4,5)P2/PI and PI(4,5)P2/PS. In addition to this kinetic work, we will also present a novel model membrane platform that takes advantage of a microfluidic device to develop lateral lipid gradients in SLBs. This microfluidic platform, in the future, will allow for the investigation of the dynamic behavior of proteins interacting with lipids but with a bilayer that has a structure recapitulating polarized membranes like in chemotaxing cells.

Junctional adhesion molecule C (JAM-C) is a component of endothelial cell (EC) tight junctions that has been implicated in a number of endothelial functions, such as angiogenesis and trafficking of leukocytes through the endothelium during inflammation. Work within our lab has identified that loss of JAM-C at EC junctions results in increased reverse transendothelial migration (rTEM) of neutrophils back into the circulation, a response that has been associated with the dissemination of inflammation to distant organs. Whilst the mechanism by which JAM-C is lost or redistributed away from EC junctions has begun to be elucidated, little is known about how loss of endothelial JAM-C impacts the functions of ECs. As such, this thesis aimed to investigate the effect of JAM-C deficiency on EC functions to unravel possible molecular and cellular mechanisms of mediating neutrophil rTEM. To address the effect of JAM-C deficiency on EC functions, an in vitro RNA interference (RNAi) approach was used to efficiently knock-down (KD) JAM-C in human umbilical vein ECs (HUVECs). Importantly, KD of JAM-C did not affect expression of other key EC junctional markers such as JAM-A and VE-Cadherin and cell proliferation and apoptosis were similarly unaffected. Gene expression profiling using microarrays revealed that JAM-C depleted HUVECs exhibited a pro-inflammatory phenotype under basal conditions that was characterised by increased expression of pro-inflammatory genes such as ICAM1 and IL8. Following IL-1β-induced inflammation, no difference in expression of pro-inflammatory genes was detected between control and JAM-C KD HUVECs. However, protein levels of secreted chemokines such as IL-8 were reduced in JAM-C KD HUVECs following stimulation with IL-1β. This was corroborated by in vivo studies demonstrating reduced levels of secreted chemokines in the plasma of mice where JAM-C was conditionally deleted from ECs. A novel finding of this work is the demonstration that JAM-C KD HUVECs exhibit increased autophagy under basal conditions. This might provide a potential mechanism for the reduced chemokine secretion that is observed in this system, whereby chemokines are preferentially trafficked for autophagosome-mediated degradation. Taken together, these findings indicate a multi-functional role for JAM-C in regulating EC homeostasis under basal conditions. JAM-C KD ECs respond aberrantly to inflammatory stimuli by secreting reduced chemokine levels, a consequence that could provide novel insights into the mechanisms of neutrophil rTEM under conditions of endothelial JAM-C loss.

Heparan sulfate (HS) is a cell-surface sulfated polysaccharide that binds to multiple proteins and has been implicated in cancer, viral infection and Alzheimer's disease. Due to the heterogeneity of HS, the structural requirements for protein binding are ill- defined. Chemical synthesis of structurally-defined HS oligosaccharides, which are tunable in terms of length, order of monosaccharides and sulfation pattern, is required for the investigation of HS-protein binding. Single molecule methods have been utilised in biophysics to study dynamic processes and can allow observation of rare events which would be 'averaged out' in ensemble measurements. Access to fluorescently labelled HS oligosaccharides should allow investigation of interactions with proteins at the single molecule level using methods such as single molecule FRET, providing a method complementary to NMR studies (ensemble) and X-ray crystallography (non-dynamic).This thesis presents the development of a method for the fluorescent labelling of a chemically synthesised HS disaccharide utilising a reducing-end amine tag. Analysis of the fluorescence properties of the labelled disaccharide at ensemble and single molecule level indicated no perturbation of the fluorophore when attached to the sugar. Fluorescence correlation spectroscopy measurements of the fluorescent HS disaccharide with the protein FGF-1 showed no binding, which is attributed to the low concentration (1 nM) of disaccharide required in the experiment. Additional work is presented in this thesis on the development of a method for atom-specific 13C labelling of HS oligosaccharides, which has been initiated by synthesis of a 13C labelled L-iduronate monosaccharide and a 13C labelled disaccharide. New strategies for the synthesis of HS oligosaccharides based on orthogonal thioglycoside-based glycosylations employing S-benzoxazolyl and S-thiazolyl donors have been investigated. Development of a chemoselective glycosylation strategy for HS oligosaccharide synthesis utilising a 'super-disarmed' [2.2.2] L-iduronic lactone is presented.

The prevalence of stress and anxiety disorders in modern society is increasing, but the development of new treatments decreasing due to high research costs and low success rates in clinical trials. The latest type of compounds introduced to treat anxiety and depression was the specific serotonin reuptake inhibitors (SSRI), which was introduced in 1987. Since then, no new class of compounds have been introduced, suggesting that the need to find alternative targets in treating mental disorders is needed. In this thesis I have used the zebrafish as a model organism to study the modulation of behaviours through intracellular signalling pathways, known to be involved in learning, memory and anxiety. First, using the pro-convulsant compound, pentylenetetrazole (PTZ), an automated tracking system was established to quantify and analyse swimming behaviour in larvae zebrafish. Pentylenetetrazole induces seizures in zebrafish at high concentrations, however this thesis identifies that the combination of a low level of PTZ and subjecting the fish to alternating cycles of light and dark induced a reversed response to light and dark. A group of compounds with known anti-seizure effects were subsequently screened, which found that a combinational treatment with diazepam and two types of neurosteroids reversed the PTZ-induced light dark response. Secondly, using the same automated analysis setup, the effect of cAMP modulators was studied on behaviour in zebrafish larvae. Our lab has previously established that Rolipram, a PDE4 inhibitor, causes anxiety thigmotaxis in zebrafish larvae. In this thesis we treated zebrafish larvae with Rolipram and other compounds modulating cAMP, which greatly increased the swimming activity, which was reversed by subsequently treating with PD0325901. To test if the pharmacological modulation of cAMP-levels through the inhibition of other PDEs would lead to increased locomotor activity, a small library of PDE inhibitors was screened, and 4 compounds were identified that caused an increase in locomotion – three of these compounds were PDE4-inhibitors. Finally, by using two behavioural assays, I found that in adult fish Rolipram cause anxiety-like phenotypes, which is also reversible by MAPK-inhibition.

O uso de agrotóxicos e a consequente contaminação têm sido motivo de constante preocupação, sendo necessário monitorar esses compostos por metodologias que as quantifiquem em água e alimentos. As técnicas cromatográficas são as mais utilizadas para a este tipo de análise, mas apresentam desvantagens para aplicações \"in situ\" ou em tempo real. As técnicas eletroquímicas, como os biossensores enzimáticos que utilizam a acetilcolinesterase, têm sido estudadas para a determinação quantitativa de pesticidas em diferentes amostras. No entanto, as enzimas apresentam algumas desvantagens relacionadas com sua capacidade de desnaturação e com a inibição por outras espécies. Diante disso, foi proposta neste projeto a síntese de uma molécula mimética [ácido (4-(1E)-etanohidrazonoil) benzóico] para a acetilcolinesterase para catalisar a hidrólise do substrato (acetiltiocolina). A molécula mimética foi caracterizada por RMN e FTIR. Os produtos da reação, acetato e tiocolina, foram identificados pelo método de Ellman e FTIR. A cinética química do processo catalítico foi estudada, verificando-se que a reação era de primeira ordem em relação à concentração de acetiltiocolina e a constante de velocidade foi 0,623 s-1. Os dados experimentais obtidos com a molécula artificial foram aplicados ao modelo cinético de Michaelis-Menten e os parâmetros cinéticos foram determinados, constatando que a constante de velocidade calculada foi 13000 vezes menor que aquela calculada pelo método diferencial, o que mostrou a inconveniência de aplicar tal modelo enzimático aos catalisadores sintéticos. Além disso, verificou-se que o KM é uma constante que não possui significado quando aplicada às moléculas miméticas. / The application of pesticides and the resulting contamination have been a matter of constant concern, being necessary to monitor these compounds by methods that are able to quantify these compounds in water and food. The chromatographic techniques are most often used for this kind of analysis, but present some drawbacks for \"in situ\" or in real time applications. Electrochemical techniques, like biosensors based on the inhibition of acetylcholinesterase, have been studied for the quantitative determination of pesticides in different samples. However, the use of enzymes is complicated due to their ability to denaturation and the possible inhibition by other species. Therefore, in this project the synthesis of [4-(1E)etanehydrazonoylbenzoic acid], a mimetic molecule for acetylcholinesterase, was carried out, aiming the catalysis of acetylcholine hydrolysis. The mimetic molecule was characterized by NMR and FTIR. The products of reaction, such as acetate and thiocholine, were identified by Ellman\'s method and FTIR. The chemical kinetic of the catalytic process was characterized as of first order with respect to the acetylthiocholine concentration with a rate constant of 0.623 s-1. The experimental data obtained with the artificial molecule were applied to the Michaelis-Menten\'s model and the kinetic parameters were determined, noting that the rate constant was calculated as 13000 times smaller than that obtained by the differential method, which indicates the inconvenience of using the enzymatic model to the mimetic catalysts. Moreover, it was found that KM has no meaning when applied to mimetic molecules.