Ce travail de thèse réalisé à l’Institut de Chimie Moléculaire de l’Université de Bourgogne et en collaboration avec le PET Research Centre, porte sur la synthèse d’une nouvelle classe de pinces à fluorures dérivés d’aminoacides dans le but de piéger les ions [18F]-fluorures par formation d’une liaison B-F et d’évaluer leur potentiel en tant qu’agent d’imagerie TEP. Les travaux ont tout d’abord concerné la conception, la synthèse et la caractérisation des nouveaux sels de phosphoniums boronatés et trifluoroborates dérivés d’aminoacides. Ainsi, par quaternisation de l’o-boronate phényl phosphine avec des β-iodo amino esters ou des γ-iodo amino esters, les sels correspondants sont obtenus sans racémisation et avec des rendements atteignant 88%. La saponification des phosphoniums boronatés aminoesters donne les dérivés avec la fonction acide libre, tandis que l’acidolyse par HCl mène à l’amine correspondante offrant ainsi, l’opportunité d’un couplage ultérieur à une biomolécule. Ensuite, les dérivés trifluoroboratés sont facilement préparés par réaction de KHF2 en solution dans un mélange hydroalcoolique. Les études de stabilités en milieux aqueux des phosphoniums o-trifluoroborates aminoacides ont permis d’établir que ces dérivés sont extrêmement stables à l’hydrolyse. Enfin, la [18F]-radiosynthèse des sels de phosphonium boronatés a été étudiée selon deux méthodes: par échange isotopique 18F-19F direct à partir d’un trifluoroborate et par marquage direct d’un sel de phosphonium boronaté en présence d’un mélange de fluorures [18F] et KHF2. Intéressement, après une synthèse totale de 50 minutes comprenant le séchage azéotropique, la synthèse et la purification, [18F]-203c a été obtenu avec un rendement radiochimique de 10% corrigé de la décroissance, une pureté radiochimique ≥97% et une activité spécifique de 0.13 GBq/µmol. / This thesis project, which is part of a collaboration between the Institut de Chimie Moléculaire de l’Université de Bourgogne and the Positron Emission Tomography Research Centre, is about the synthesis of fluoride pincers derived from amino acids based on 18F-B bond construction to get a new class of PET imaging agents. First, this project concerned the design, synthesis and characterisation of new boronato and trifluoroborato phosphonium amino acid salts. Quaternisation of o-boronate phenyl phosphine with β-iodo amino esters or γ-iodo amino ester leads to the corresponding salts without racemisation and in yields up to 88%. Saponification of boronato phosphonium amino esters afford the free carboxylic acid derivatives, whereas HCl acidolysis leads to the corresponding amino compounds which offers the opportunity of further biomolecule coupling. Then, o-trifluoroborate phosphonium salts are efficiently prepared by reaction with KHF2 in solution on hydroalcoholic mixture. The kinetic stabilities of these o-trifluoroborate phosphoniums have shown extremely stable compounds to hydrolysis. Finally, [18F]-radiosyntheses of phosphonium salts was studied according to two methods : by 18F-19F isotopic exchange from trifluoroborate or by carrier added preparation of [18F]-fluoride ions from boronate phosphonium salts. Satisfactingly, after a total synthesis of 50 minutes (including azeotropic drying, synthesis and purification), [18F]-203c was obtained with a RCY on 10% decay corrected, a RCP ≥ 97% and a specific activity of 0.13 GBq/µmol.

The thesis entitled ‘Studies on the Chemistry of Carbonates and Carbamates’ comprises of seven chapters. Chapter 1 The reactivity of propargyloxycarbonyl (Poc) derivatives of amines and alcohols with various sulphur nucleophiles is addressed in this chapter. The chapter is divided into three different parts. Part 1: The difference in reactivity of propargyloxycarbonyl (Poc) derivatives of amines and alcohols with benzyltriethylammonium tetrathiomolybdate [(PhCH2NEt3)2MoS4, 1] is studied in detail and the results are discussed. It has been shown that amino alcohols can be protected as their diPoc derivatives using 2 equiv of propargyloxycarbonyl chloride (2). The selective deprotection of the O-Poc group using 1 equiv of 1 without affecting the N-Poc group is achieved (Scheme 1). Scheme 1 Part 2: The reactivity of propargyloxycarbonyl derivatives of various alcohols, phenols and primary and secondary amines with benzyltriethylammonium tetrathiomolybdate (1) is compared with the reactivity of these Poc derivatives with other sulphur nucleophiles such as sodium thiophenoxide, lithium sulphide, hydrogen sulphide and ammonium sulphide. The study reveals that tetrathiomolybdate (1) is the best sulphur nucleophile for the deprotection of Poc group. Poc derivatives of primary amines cyclized to the corresponding 4-methylene-2-oxazolidinones when treated with other sulphur nucleophiles (Scheme 2). Scheme 2 Part 3: The reaction between different propargyloxycarbonyl derivatives of alcohols and benzyltriethylammonium tetrathiomolybdate (1) is studied. It is found that propargyloxycarbonyl derivatives can be made more reactive towards tetrathiomolybdate by substituting the propargyl system with electron withdrawing substituents. Chapter 2 The application of propargyloxycarbonyl group for the protection of the side chain hydroxyl groups of serine, threonine and tyrosine is discussed. The O-Poc derivatives are shown to be stable to a variety of acidic and basic conditions and the applications of these derivatives in solution phase peptide synthesis is addressed. The easy and effective deprotection of the O-Poc group provides a new strategy for the synthesis of peptides bearing the hydroxy amino acid residues: serine, threonine and tyrosine. Scheme 3 Chapter 3 Development of a novel C2-symmetric protecting group for amines and amino acids is described in this chapter. But-2-ynyl-1,4-bisoxycarbonyl chloride (BbcCl, 3) is synthesized from 1,4-dihydroxybut-2-yne and used as a reagent for protecting amines as biscarbamates (Scheme 4). These biscarbamates (Bbc derivatives) are deblocked using benzyltriethylammonium tetrathiomolybdate (1) to get the amines back. Scheme 4 The orthogonal stability of the Bbc group with Boc, Cbz and Fmoc groups is established. It is also shown that Bbc group can be deblocked to the corresponding amines using resin-bound tetrathiomolybdate. The application of Bbc protected amino acids in solution phase peptide synthesis is demonstrated (Scheme 5). Scheme 5 Chapter 4 The simultaneous protection and activation of amino acids using various pentafluorophenyl carbonates is described in two parts. Part 1: A very efficient and high yielding method for the simultaneous protection of the amino group and activation of carboxylic acid group using propargyl pentafluorophenyl carbonate (PocOPfp, 4) is discussed. Treating amino acids with 2 equiv of 4 protects the amino group as a propargyl carbamate and activates the carboxylic acid group as a pentafluorophenyl ester (Scheme 6). Scheme 6 Part 2: The generality of the methodology developed for the simultaneous protection and activation of amino acids using PocOPfp (4) is studied with five different pentafluorophenyl carbonates viz. AlocOPfp, CbzOPfp, BocOPfp, EocOPfp and TrocOPfp. The studies reveal that the effectiveness of the methodology depends on the nature of the pentafluorophenyl carbonates and on the nature of the amino acids. Sterically bulky pentafluorophenyl carbonates such as BocOPfp reacted slowly with amino acids while electron deficient pentafluorophenyl carbonates such as TrocOPfp reacted faster and gave the N-protected active esters in very good yields. Amino acids bearing longer aliphatic side chains reacted better than the other amino acids. Chapter 5 The chapter describes results of the detailed studies on the base catalyzed cyclization of N-alkyl and N-aryl-O-propargyl carbamates to the corresponding 4-alkylidene-2-oxazolidinones. The effect of various bases and solvents on these cyclization reactions is studied systematically to design the most suitable conditions. The best results were obtained using catalytic amount of LiOH in DMF. The cyclization reactions of N-aryl-O-propargyl carbamates were faster than the cyclization of N-alkyl-O-propargyl carbamates. The effect of substitutions on the propargyl group in these reactions is studied by preparing various substituted propargyl carbamate derivatives from the corresponding amines and propargyl chloroformates (Scheme 7). Scheme 7 Chapter 6 An efficient procedure for the synthesis of dehydroalanine and dehydroamino butyric acid derivatives from the preformed carbonate derivatives of serine and threonine respectively, by treating with K2CO3 in DMF is discussed in this chapter. The reaction proceeds stereoselectively through a trans E2-elimination pathway to give only the Z-isomer of dehydroamino butyric acid derivatives from the carbonate derivatives of threonine. The methodology offers an easy access to dehydropeptides and proceeds without racemization of other stereogenic centers present in the peptide (Scheme 8). Scheme 8 Chapter 7 This chapter describes the use of propargyloxycarbonyl derivatives of lysine as an efficient tool for the synthesis of peptide conjugates using a click chemistry approach. The Cu(I) catalyzed cycloaddition reaction between azides and alkynes is employed in the synthesis of conjugates of lysine. Peptides bearing an Nε-Poc Lysine residue can be synthesized using traditional strategies and these peptides can be easily conjugated with azide derivatives of sugars and amino acids (Scheme 9). Scheme 9 The efficiency of the method is demonstrated by carrying out more than one click reaction in one pot using di and tri-propargyl derivatives of lysine. A dendritic core (6) is prepared from a tri-propargyl derivative (5) of lysine and an azide derived from leucine (Scheme 10). Scheme 10 The abbreviations used in the thesis are consistent with those reported in J. Org. Chem. 2007, 71, 23A. Less common abbreviations are defined, the first time they are mentioned in the thesis.

Orientador: Jaime Amaya-Farfan / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T12:35:54Z (GMT). No. of bitstreams: 1 Zaffani_VivianeCostaSilva_M.pdf: 1237742 bytes, checksum: 013e4cb87532470b0d0ebff8e7ade481 (MD5) Previous issue date: 2009 / Resumo: A ocorrência de desvios no metabolismo protéico durante o exercício depende tanto da intensidade, duração e freqüência do exercício, como também da ingestão alimentar, especialmente da qualidade da dieta consumida. Neste contexto, proteína do soro do leite (PSL) destaca-se pelo seu alto valor nutritivo, devido tanto à composição de aminoácidos, quanto à rápida digestão, além de outras funcionalidades relacionadas com a saúde. O objetivo deste estudo foi avaliar em ratos os efeitos da ingestão da proteína do soro do leite, na sua forma intacta e hidrolisada (~12,5% de hidrólise), em associação à atividade física de endurance, sobre os níveis séricos de aminoácidos, evolução ponderal, conteúdo protéico em gastrocnêmio e sóleo, conteúdo de DNA no gastrocnêmio, níveis séricos de IGF1, síntese e degradação protéica no grastrocnêmio e síntese no sóleo. Ratos Wistar foram distribuídos em 6 grupos, de acordo com a proteína consumida (12%): caseína (CAS), isolado protéico do soro do leite (IPSL) ou hidrolisado protéico do soro do leite (HPSL)) e submetidos a um protocolo de atividade física (sedentários (S) e treinados (T)). Os ratos treinados correram em esteira, durante 9 semanas, e foram sacrificados após 48 horas de repouso e 12 horas de jejum. As três dietas utilizadas apresentaram conteúdos semelhantes de aminoácidos totais, mas as dietas IPSL e HPSL destacaram-se apresentando maiores valores absolutos de leucina, isoleucina, lisina, treonina, cistina, alanina e ácido aspártico, em relação a CAS. No geral, os níveis séricos de aminoácidos indispensáveis foram semelhantes para os grupos IS e HS, em comparação com os ratos controle sedentários (CS), enquanto o grupo HT apresentou o maior nível destes aminoácidos, em relação ao CT. A evolução ponderal foi semelhante para todos os grupos de ratos até o final da oitava semana de treinamento. Na nona semana, os grupos treinados apresentaram peso significativamente menor que o CS. Não houve diferença estatística para o peso, conteúdo protéico dos músculos gastrocnêmio e sóleo, níveis séricos de IGF1 e taxas de degradação protéica muscular do gastrocnêmio, entre todos os grupos experimentais. O conteúdo e concentração de DNA no gastrocnêmio foi significativamente menor em ambos os grupos que consumiam a HPSL (HS e HT), independente da atividade física, comparado aos grupos que consumiam as proteínas intactas (CS, IS, CT e IT). As taxas de síntese protéica nos músculos gastrocnêmio e sóleo também foram menores para o grupo HT, comparado aos sedentários (CS, IS e HS), mas sem mostrar diferença com os grupos CT e IT. Os ratos do grupo HT destacaram-se por apresentar diminuição da demanda por nova síntese protéica, e da necessidade de utilização de aminoácidos do pool sérico diminuindo, consequentemente, a necessidade de aumentar a quantidade de DNA celular no músculo gastrocnêmio e ainda assim, manteve o peso, a concentração e o conteúdo protéico muscular sem diferença em relação aos demais grupos. Estes resultados, considerados em conjunto, sugerem que o consumo da proteína hidrolisada do soro do leite pode contribuir para a preservação da massa muscular no gastrocnêmio, quando associado à atividade física de endurance. / Abstract: Physical exercise promotes protein metabolic alterations depending not only on its intensity, duration and frequency, but also on food intake and especially on the quality of the diet. In this context, the milk whey proteins (PSL) stand out because of their high quality, meeting both amino-acid profile and digestibility requirements, besides other functional properties. The aim of this study was to assess the effects of milk whey protein intake in rats, in both the intact and hydrolyzed forms (~12,5% of hydrolysis), associated with physical activity of endurance, on serum amino acids levels, body weight, protein content in both the gastrocnemius and soleus muscles, total DNA content in the gastrocnemius, serum IGF1 levels, protein degradation rate in the gastrocnemius, and of protein synthesis in the soleus and gastrocnemius. Male Wistar rats were divided into six groups as follows: protein consumed (12%), casein - CAS, milk whey protein isolate - IPSL, or milk whey protein hydrolyzate -HPSL) and physical activity protocol (sedentary, S, and trained, T). The trained rats were exercised on the treadmill during nine weeks and sacrificed following 48 hours of rest; the last 12 hours being fasted. The three diets tested produced similar contents of total amino acids, although the IPSL and HPSL diets stood out because of the higher absolute values of leucine, isoleucine, lysine, threonine, cysteine, alanine and aspartate than those of CAS. As a whole, the serum indispensable amino acid levels were similar when comparing both IS and HS groups with the control group (CS). However, the HT group showed higher levels of these amino acids than the CT group. No difference in body weight evolution was apparent among the groups until the end of the eighth week of training. Nevertheless, on the ninth week the trained groups showed significantly lower weights than group CS. There were no significant differences, among all groups studied, in the weight, the content and concentration of both gastrocnemius and soleus muscles, and serum IGF1 levels, as well as the degradation rate of proteins in the gastrocnemius muscle. The content and concentration of DNA in the gastrocnemius were significantly lower in both groups fed HPSL (HS and HT), regardless of physical activity, than in the groups fed intact protein (CS, IS, CT and IT). The rate of protein synthesis in both gastrocnemius and soleus muscles were also lower in the HT group than those found in the CS, IS and HS groups. However, there was no difference when compared to those of the IT and CT groups. Summarizing, the HT group stood out because of its lower demand for new protein synthesis and amino acid utilization from the serum pool, consequently decreasing the need for higher amount of cellular DNA in the gastrocnemius muscle. Even so, this group kept the same muscle mass, protein content and concentration, as those of the other groups. These results suggest that the consumption of hydrolyzed milk whey protein may contribute to the preservation of the gastrocnemius muscle when associated with physical activity of endurance. / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição

Origin of life is a still-enduring gap in human knowledge. This work is focused on revealing of several pieces of this puzzle. State of the art scenarios of biomolecules synthesis under prebiotic conditions are presented and discussed. This thesis presents our recent experiments suggesting a novel idea that neutral planetary atmosphere containing a mixture of neutral volcanic-type gasses (CO2, N2, H2O) can be converted over acidic mineral catalysts upon irradiation by a soft UV-radiation into a relatively reactive mixture of reducing gases (CH4, CO), which can be further reprocessed by high-energy chemistry. The resulting mixture (CH4, CO + N2) represents a common reducing atmosphere related e.g. to the chemistry of Titan, the largest moon of Saturn, as well as a possible representation of the secondary atmosphere of our planet. Also, photocatalytic reduction of CO2-rich atmosphere can explain the abiotic origin of methane on current Mars or other terrestrial planets. In our subsequent experiments, corresponding equimolar model mixture of CH4 : CO : N2 in presence of water vapour was subjected to reprocessing by high-power laser plasma simulating an asteroid impact - one of a series of impact events which the young Earth experienced during the first 600 million years of her history. Upon delivery...

The laboratory-made apparatus for electrophoretic separations in short capillaries has been tested. The basic functions of the apparatus (separation efficiency, resolution, migration time) have been tested using mixture of K+ and Na+ ions. The model mixture of basic amino-acids (arginine, lysine, histidine and its derivatives, 3-methylhistidine and 1-methylhistidine) has also been separated and detected using contactless conductometric detector. Histidine in real sample of urine has also been determined. Keywords: capillary electrophoresis, short capillary, alkaline aminoacids

This Master thesis investigates the interaction between the polysaccharide sodium hyaluronate (HA) and some amphiphilic molecules. It is known that the presence of the carboxylic group on HA and the aminogroup on the amphiphiles leads to electrostatic interaction between these two compounds. This supposal offers the possibility to physically modify HA and use it as a new type of a carrier of bioactive compounds, for example medicals. However, successful carrier of bioactive compound has to resist a certain value of ionic strength. The high-molecular weights HA (1.75MDa) and amphiphile lysine were chosen for the study of the influence of ionic strength on the system HA – amphiphile. Our results show that system HA – amphiphile system is suppressed even by low concentrate solution of electrolyte. Therefore the system was reinforced by protonation of the aminoacid. The results show, that the interactions were reinforced, nevertheless negative influence of chlorine anions had to be eliminated by lyophilization. The solutions with strengthened system HA – amphiphile were used for the research of ionic strength influence. The amphiphiles lysine, 6 - aminocaproic acid and arginine were selected for this study. The interactions were investigated by means of reometry and conductometry.

No description available.

Les acides α-aminés non naturels forment une famille de composés incontournables pour la conception de peptidomimétiques. Plus précisément, l'utilisation du silicium comme isostère du carbone sur la chaîne latérale des acides α-aminés a été largement reportée dans la littérature, montrant alors l'importance d'une telle modification. En particulier, compte tenu du rôle fondamental que joue la proline dans la structuration des peptides, et des avantages que peut apporter le silicium, il nous a paru intéressant de nous centrer sur la silaproline. Après avoir mis au point une synthèse permettant la production de la silaproline à grande échelle, nous avons mis au point la préparation d'homopolypeptides de ce résidu particulier. Dans un premier temps des oligomères monodisperses de silaproline ont été synthétisés. L'étude structurale par RMN, CD et modélisation moléculaire a permis de confirmer la conformation préférentielle en hélice polyproline de type II (PPII). Ensuite la synthèse de polymères plus longs, obtenus par polymérisation de N-carboxyanhydrides a été développée. Ces nouveaux biopolymères ainsi préparés ont conduit à des mimes de PPII lipophiles. Enfin, une nouvelle voie de polymérisation, dans des conditions douces, par réaction d'esters, a été optimisée, permettant d'accéder facilement à des polypeptides. / Unnatural α-amino acids form a family of essential compounds for the design of peptidomimetics. More specifically, the use of silicon as an isostere of carbon on the side chain of α-amino acids has been widely reported in the literature, while demonstrating the importance of this modification. In particular, the fundamental role of proline in peptide structures, and the advantage of the silicon, promoted us to focus on the silaproline.After the development of a gram scale synthesis of silaproline, we prepared homopolypeptides of this particular residue. Firstly, monodisperse silaproline oligomers were synthesized. The structural study by NMR, CD and molecular modeling confirmed the conformational preference for polyproline type II helix (PPII). Then longer polymers were obtained by polymerization of N-carboxyanhydrides. These new biopolymers were prepared, leading to more lipophilic PPII mimics.Finally, a new way of polymerization by reacting esters under mild conditions has been optimized for easy access to polypeptides.

Os carboidratos apresentam-se envolvidos em diversos eventos celulares, tais como geração de energia, sustentação celular, reconhecimento celular, processos de sinalização, etc. A OGlcNAcilação, uma das alterações proteicas pós-traducionais relacionada à adição de Nacetilglicosamina a resíduos de serina ou treonina em proteínas citoplasmáticas ou nucleares, vem demonstrando ser uma das alterações recíproca a O-fosforilação de proteínas e pode estar envolvida no desencadeamento de patologias como câncer, diabetes tipo II, e doenças neurodegenerativas. Tendo em vista à relevância da O-GlcNAcilação e a necessidade de ferramentas para seu estudo, temos como objetivo, desenvolver uma rota sintética para a obtenção de moléculas modificadas derivadas de N-acetilglicosamina, contendo o átomo de flúor ligado ao grupo N-acetil. As moléculas correspondem aos derivados glicopiranosídeo de metila 1 e glicoaminoácidos de serina 2 e treonina 3. Uma vez padronizada, os intermediários finais da rota serão utilizados para futura marcação com o 18F, o qual poderá ser empregado em estudos do processo de sinalização celular por O-GlcNAcilação, e no diagnóstico de câncer por PET. Assim, foram propostas, inicialmente, duas rotas sintéticas, uma para a síntese do derivado glicopiranosídeo de metila 1 e outra para os glicoaminoácidos 2 e 3, ambas utilizando o reagente cloridrato de 2-amino-2-desoxi-D-glicose (4) como percursor. A síntese do derivado 1 foi conduzida por meio da proteção do grupo amino do composto 4 pela formação de carbamato 5, e sequencial reação de glicosilação de Fischer (6 e 7), per-Oacetilação 8 e remoção do grupo protetor do amino 9. As etapas sequenciais relacionadas à condensação com o ácido bromoacético 10, e finalmente halogenação e desproteção do carboidrato 11 estão em andamento. A rota sintética proposta para a obtenção dos glicoaminoácidos 2 e 3 foi fundamentada na obtenção de um doador glicosídico contendo o grupo tricloroacetimidato e as hidroxilas protegidas com grupos benzílicos 16, e na utilização do aceptor glicosídico serina 17 e treonina 18, contendo os grupos amino e carboxila protegidos com 9-fluorenilmetóxicarbonil (Fmoc) e benzil (Bn), respectivamente. Até o momento não foi possível a síntese dos glicoaminoácidos 2 e 3 empregando o doador glicosídico inicialmente proposto (tricloroacetimidato), e mesmo após a variação do doador glicosídico, empregando tioaçucares per-O-benzilado 28, ou per-O-acetilado 26, não foi possível a obtenção do produto desejado. As dificuldades observadas na obtenção dos compostos, conduziram a elaboração de novas estratégias sintéticas que possuem o átomo de cloro como grupo abandonador na posição anomérica e a) uma amida {[(4- metilfenil)sulfonil]oxi}acético (33) em C-2, a qual exerce assistência anquimérica em C-1, e permite a funcionalização com o flúor e b) um azido em C-2, preparado a partir de glicais per- O-acetilados, desprovido de participação em C-1. Ambas as rotas sintéticas estão em andamento. / Carbohydrates are involved in many cellular events, such as energy source, sustenance, recognition, signaling processes, etc. O- GlcNAcylation is a post- translational proteins\' alteration related to the addition of N-acetylglucosamine to residues of serine or threonine in cytoplasmic or nuclear protein which has proven to be one of the reciprocal changes to Ophosphorylation of proteins and may be involved in the onset of pathologies such as cancer, type II diabetes, and neurodegenerative diseases. Given the relevance of O- GlcNAcylation and the importance of tools required for the study of this event, we aim to develop a synthetic route to obtain modified molecules derived from N-acetylglucosamine containing fluorine atom attached to the N -acetyl group. The molecules correspond to methyl glucopyranoside derivatives 1 and gluco-amino acids derived from serine 2 and threonine 3. Once the synthetic route is established, the final intermediates of the route will be used for further labeling with 18F, which may be employed in studies of cell signaling processes, involving OGlcNAcylation, and cancer diagnosis by PET. Thus, two synthetic routes were initially proposed: one for the preparation of the methyl glucopyranoside derivative 1 and another one for the gluco-amino acids 2 and 3, both using glucosamine hydrochloride (4) as a precursor. The synthesis of derivative 1 was conducted by protecting the amine group of compound 4 to form the carbamate 5, and sequential Fischer glycosylation (6, 7), per-O-acetylation (8) and removal of the protecting group from the amine (9). The sequential steps related to condensation with bromoacetic acid (10), halogenation and deprotection of the carbohydrate 11 are in progress. The proposed synthetic route for the preparation of 2 and 3 was based on a glycosidic donor containing trichloroacetimidate group, the protection of the hydroxyl groups with benzyl group (16) and glycoside acceptors serine 17 and threonine 18 containing amine and carboxyl groups protected with 9- fluorenylmethoxycarbonyl (Fmoc) and benzyl (Bn), respectively. Hitherto, the synthesis of gluco-amino acids 2 and 3 was not achieved using the glycosidic donor initially proposed (trichloroacetimidate), even after the change of the glycosidic donor using per-O-benzylated (28) or per-O-acetylated (26) thiosugars. The difficulties encountered for the synthesis of the target compounds led the design of new synthetic strategies which comprise a chlorine atom as leaving group in the anomeric position and either: a) an amide acetic acid (33) at C-2, which exerts anchimeric assistance at C-1, and allows functionalization with fluorine and b) an azide group at C- 2, prepared from per-O-acetylated glucal, with no participation at C-1. Both synthetic routes are in progress.

O presente trabalho apresenta metodologias utilizando a p-benzoquinona (PBQ) para a determinação de proteínas totais em diversas matrizes. As metodologias propostas foram comparadas com os métodos recomendados ou os mais utilizados, conforme o caso. O método aqui proposto, para determinação de proteínas totais em plasma sangüíneo, foi comparado com o método de biureto, mostrando-se adequado e com sensibilidade dez vezes maior que a do biureto. Para a determinação de proteínas totais em diversos tecidos de rato, o método proposto foi comparado com os métodos de Hartree e FFDW, e apresentou resultados mais próximos do FFDW do que o método de Hartree e, também, mostrou ser mais rápido, barato e de fácil realização. O método desenvolvido para determinação de proteínas totais em leite em pó desnatado foi comparado com os métodos de Kjeldahl e Lowry e cols., sendo mais simples e rápido que as metodologias de Lowry e Kjeldahl. Para determinação de amino grupos livres em síntese de peptídeos em fase sólida, a metodologia proposta foi comparada com o método de Kaiser e cols. O método proposto apresentou diversas vantagens sobre o método de Kaiser, sendo estas: o método é sensível a prolina, não precisa preparar nenhuma solução, não apresenta falso positivo para histidina e é rápido. / The present thesis describes the utilization of p-benzoquinone (PBQ) for assay of total protein in several samples. The methods presented here were compared with those mostly used or recommended depending on the case. For determination of total proteins in the blood plasma, the proposed method was compared with biuret method, and it was 10 times more sensitive than biuret method and convenient method for determination of total proteins in plasma. The assay of total proteins in several rat tissues with the proposed method, was compared with Hartree and FFDW methods, and it shows closer proteins content to FFDW method than Hartree method, besides it was faster, less expensive and easier to be used than Hartree method. The method developed for determination of total proteins in skin milk powder, was compared with Kjeldahl and Lowry methods and showed to be more simple and faster than these methods. For determination of free amino groups in solid phase peptide synthesis, the proposed method was compared with Kaiser method. The proposed method showed several advantages than Kaiser method, such as: it is sensitive for proline, it is not necessary to prepare any solution and it does not show a false positive test for histidine.