Mainz, Univ., Diss., 2001.

Techn. University, Diss., 2002--Berlin.

Universiẗat, Diss., 2002--Münster (Westfalen).

Neuste Studien haben ergeben, dass Asc-1 Knock-out Mäuse aufgrund einer verminderten intrazellulären Glycinkonzentration in synaptischen Boutons im Gehirn, einen Hyperekplexie-ähnlichen Phänotyp entwickeln. Aufgrund nicht vollständig geklärter Ursachen für die Entstehung des Krankheitsbildes der Hyperekplexie beim Menschen, wurde eine Kohorte von 51 Patienten zusammengetragen, um vor dem Hintergrund der Forschungsergebnisse zu Asc-1 im Tiermodell, das kodierende Gen beim Menschen SLC7A10 als mögliches Kandidatengen auf Sequenzalterationen zu untersuchen. Hierfür wurde aus Vollblut der an Hyperekplexie erkrankten Patienten genomische DNA isoliert, um mittels PCR und anschließendem Screening der Sequenzen, Mutationen innerhalb funktionell wichtiger Bereiche des Gens zu eruieren. Neben weiteren Sequenzunterschieden, die meist in Introns gefunden wurden, wurde die codierende Mutation G307R innerhalb von Exon 7 identifiziert, die letztendlich der Grund für eine Versuchsreihe war, um zu hinterfragen, ob dieser Aminosäureaustausch in der Proteinsequenz funktionelle Konsequenzen zur Folge hat. HEK293-Zellen wurden mit dem zuvor hergestellten Klon G307R transfiziert, um über Biotinylierung, immuncytochemische Färbungen und funktionelle Untersuchungen die Aktivität des Transporters zu beurteilen. Hier zeigte sich ein Funktionsverlust von über 95 %, bei uneingeschränkter Oberflächenexpression. ASC-1 bestätigt sich damit als neue Ursache in der Ausprägung von Hyperekplexie. Ferner können Zusammenhänge mit geistiger Retardierung und eingeschränkter neuronaler Plastizität bestehen. / Recent studies have shown that Asc-1 knock-out mice leads to reduced intracellular glycine concentration in synaptic boutons in the brain followed by a development of a hyperekplexia-like phenotype. In humans, the underlying cause for hyperekplexia is not complexly understood. Based on findings in the Asc-1 knockout mouse model, a patient cohort of 51 patients was used to identify possible sequence alterations in the corresponding Gen SLC7A10 as a novel candidate gene for human hyperekplexia. For this purpose, genomic DNA was extracted from blood samples of patients suffering from hyperekplexia to identify mutations within functionally important areas of the gene by means of PCR and subsequent analyses of the determined sequences. Besides other sequence alterations mainly in introns, the coding mutation G307R within exon 7 was identified and used to investigate functional consequences of this amino acid exchange in an experimental series. The clone ACS-1 G307R was transfected into HEK293 cells to assess the activity of the transporter via biotinylation, immunocytochemical stainings, and functional uptake assays. Our results showed an almost loss of function with more than 95 % reduction in the transport activity although surface expression was unaffected. In conclusion, the ASC-1 mutation was confirmed as a novel cause for human hyperekplexia. In addition, mental retardation and restricted neuronal plasticity might play a role during disease manifestation.

Mutationen im Glycintransporter 2 (GlyT2) stellen die präsynaptische Komponente der neurologischen Erkrankung Hyperekplexie oder Startle Disease dar. Der neuronale Na+/Cl- -abhängige GlyT2 ist für das Recycling von Glycin verantwortlich und bildet an inhibitorischen glycinergen Synapsen die Hauptquelle des freigesetzten Transmitters. Dominante, rezessive und zusammengesetzte heterozygote Mutationen wurden bereits identifiziert, von denen die meisten zu einer beeinträchtigten Glycinaufnahme führen. In dieser Arbeit konnten wir eine neue pathogene Mutation innerhalb des neuronalen Glycintransporter-2-Gens (SLC6A5, OMIM604159) in einer Familie identifizieren, in der beide Elternteile heterozygote Träger waren. Ein homozygotes Kind litt an schweren neuromotorischen Defiziten, wohingegen Heterozygote keine Symptome aufwiesen. Die neue rezessive Mutation c.1286C>T erzeugte einen missense Aminosäureaustausch von Prolin gegen Leucin an Position 429 (pP429L) in der Transmembrandomäne 5. Wir haben die GlyT2P429L-Variante mittels Homologiemodellierung, immuncytochemischer Färbungen, Western Blot Analysen, Biotinylierung und funktioneller Glycinaufnahmetests charakterisiert. Der mutierte GlyT2 zeigte beim Proteintransport durch verschiedene intrazelluläre Kompartimente zur Zelloberfläche keine Defizite. Die gesamte Proteinexpression war jedoch signifikant verringert. Obwohl GlyT2P429L an der Zelloberfläche vorhanden ist, zeigte er einen Verlust der Proteinfunktion. Die Co-Expression der Mutante mit dem Wildtyp-Protein, die die Situation der Eltern widerspiegelte, hatte keinen Einfluss auf die Transporterfunktion und erklärte somit ihren nicht symptomatischen Phänotyp. Wenn jedoch die Mutante im Vergleich zum Wildtyp-Protein im Überschuss exprimiert wurde, war die Glycinaufnahme signifikant verringert. Die Strukturanalyse ergab, dass der eingeführte Leucinrest an Position 429 zu Konformationsänderungen in der α-Helix 5 führt, die in unmittelbarer Nähe zur Natriumbindungsstelle des Transporters lokalisiert sind. Dies deutet darauf hin, dass die Zugangsmechanismen des GlyT2 gestört sein könnten und einen vollständigen Verlust der Transportaktivität verursachen. Unsere Ergebnisse belegen, dass P429 in GlyT2 ein strukturell wichtiger Aminosäurerest ist, der eine wichtige funktionelle Rolle beim Glycintransport spielt. / Glycine transporter 2 (GlyT2) mutations represent the presynaptic component of the neurological disease hyperekplexia or startle disease. The neuronal Na+/Cl- -dependent GlyT2 is responsible for glycine recycling and establishes the main source of releasable transmitter at inhibitory glycinergic synapses. In humans, dominant, recessive and compound heterozygous mutations have been identified, most of them leading to impaired glycine uptake. In this study, we identified a novel pathogenic mutation within the neuronal GlyT2 gene (SLC6A5, OMIM604159) in a family with both parents being heterozygous carriers. A homozygous child suffered from severe neuromotor deficits, whereas heterozygous individuals did not reveal any symptoms. The novel recessive mutation c.1286C>T generated a missense amino acid exchange of proline to leucine at position 429 (pP429L) in transmembrane domain 5 of the protein. We characterized the GlyT2P429L variant using homology modeling, immunocytochemical stainings, Western blot analysis, biotinylation, and functional glycine uptake assays. The mutated GlyT2 revealed no deficits in protein trafficking through various intracellular compartments to cellular surface. However, the whole cell protein expression was significantly decreased. Although present at cellular surface, GlyT2P429L showed a loss of protein function. Co-expression of the mutant with the wild-type protein, reflecting the situation in the parents, did not affect transporter function, thus explaining their non-symptomatic phenotype. Nevertheless, when the mutant was expressed in excess compared with the wild-type protein, glycine uptake was significantly reduced. Structural analysis revealed that the introduced leucine residue at position 429 leads to conformational changes in α-helix 5 which is localized in close proximity to the sodium-binding site of the transporter. The data suggest that the gating mechanism of GlyT2 might be disturbed and causes a complete loss of transport activity. Thus, our results support P429 in GlyT2 as structurally important residue displaying a key functional role in glycine transport.

Method, so called “glycin- nitrate process”, combined with high temperature solid state reaction, of preparation multi- component ceramic perovskite materials was studied. Two types of perovskite systems were prepared by this method. Firs one, based on LaNiO3 doped by calcium and aluminium and second one, based on SmFeO3 doped by calcium and nickel or cobalt. This method made possible preparation of one phase perovskite or perovskites with few percent of nickel in form of oxide. In systems containing both nickel and calcium another phases rich in calcium and nickel appeared.

Techn. Universiẗat, Diss., 2006--Darmstadt.

In the central nervous system, excitatory and inhibitory signal transduction processes are mediated by presynaptic release of neurotransmitters, which bind to postsynaptic receptors. Glycine receptors (GlyRs) and GABAA receptors (GABAARs) are ligand-gated ion channels that enable synaptic inhibition. One part of the present thesis elucidated the role of the GlyRα1 β8 β9 loop in receptor expression, localization, and function by means of amino acid substitutions at residue Q177. This residue is underlying a startle disease phenotype in the spontaneous mouse model shaky and affected homozygous animals are dying 4-6 weeks after birth. The residue is located in the β8 β9 loop and thus part of the signal transduction unit essential for proper ion channel function. Moreover, residue Q177 is involved in a hydrogen network important for ligand binding. We observed no difference in ion channel trafficking to the cellular membrane for GlyRα1Q177 variants. However, electrophysiological measurements demonstrated reduced glycine, taurine, and β alanine potency in comparison to the wildtype protein. Modeling revealed that some GlyRα1Q177 variants disrupt the hydrogen network around residue Q177. The largest alterations were observed for the Q177R variant, which displayed similar effects as the Q177K mutation present in shaky mice. Exchange with structurally related amino acids to the original glutamine preserved the hydrogen bond network. Our results underlined the importance of the GlyR β8 β9 loop for proper ion channel gating. GlyRs as well as GABAARs can be modulated by numerous allosteric substances. Recently, we focused on monoterpenes from plant extracts and showed positive allosteric modulation of GABAARs. Here, we focused on the effect of 11 sesquiterpenes and sesquiterpenoids (SQTs) on GABAARs. SQTs are compounds naturally occurring in plants. We tested SQTs of the volatile fractions of hop and chamomile, including their secondary metabolites generated during digestion. Using the patch-clamp technique on transfected cells and neurons, we were able to observe significant GABAAR modulation by some of the compounds analyzed. Furthermore, a possible binding mechanism of SQTs to the neurosteroid binding site of the GABAAR was revealed by modeling and docking studies. We successfully demonstrated GABAAR modulation by SQTs and their secondary metabolites. The second part of the thesis investigated three-dimensional (3D) in vitro cell culture models which are becoming more and more important in different part of natural sciences. The third dimension allows developing of complex models closer to the natural environment of cells, but also requires materials with mechanical and biological properties comparable to the native tissue of the encapsulated cells. This is especially challenging for 3D in vitro cultures of primary neurons and astrocytes as the brain is one of the softest tissues found in the body. Ultra-soft matrices that mimic the neuronal in vivo environment are difficult to handle. We have overcome these challenges using fiber scaffolds created by melt electrowriting to reinforce ultra-soft matrigel. Hence, the scaffolds enabled proper handling of the whole composites and thus structural and functional characterizations requiring movement of the composites to different experimental setups. Using these scaffold-matrigel composites, we successfully established methods necessary for the characterization of neuronal network formation. Before starting with neurons, a mouse fibroblast cell line was seeded in scaffold-matrigel composites and transfected with the GlyR. 3D cultured cells displayed high viability, could be immunocytochemically stained, and electrophysiologically analyzed. In a follow-up study, primary mouse cortical neurons in fiber-reinforced matrigel were grown for up to 21 days in vitro. Neurons displayed high viability, and quantification of neurite lengths and synapse density revealed a fully formed neuronal network already after 7 days in 3D culture. Calcium imaging and patch clamp experiments demonstrated spontaneous network activity, functional voltage-gated sodium channels as well as action potential firing. By combining ultra-soft hydrogels with fiber scaffolds, we successfully created a cell culture model suitable for future work in the context of cell-cell interactions between primary cells of the brain and tumor cells, which will help to elucidate the molecular pathology of aggressive brain tumors and possibly other disease mechanisms. / Im zentralen Nervensystem wird die exzitatorische und inhibitorische Signaltransduktion durch die präsynaptische Ausschüttung von Neurotransmittern, die an postsynaptische Rezeptoren binden, gesteuert. Glycinrezeptoren (GlyRs) und GABAA-Rezeptoren (GABAARs) sind ligandengesteuerte Ionenkanäle, die die synaptische Inhibition ermöglichen. Ein Teil der vorliegenden Arbeit beschäftigt sich mit dem Einfluss des GlyRα1 β8 β9-Loops auf Expression, Lokalisation und Funktion des Rezeptors. Dazu wurde ein Aminosäureaustausch an Position Q177 durchgeführt, welche dem Startle-Krankheit-Phänotyp des spontanen Mausmodells shaky zugrunde liegt. Betroffene homozygote Tiere versterben 4-6 Wochen nach Geburt. Die Position befindet sich im β8 β9-Loop und ist damit Teil einer Signaltransduktionseinheit, die essenziell für die korrekte Rezeptorfunktion ist. Zudem ist Position Q177 teil eines Wasserstoffbrückennetzwerks, welches für die Ligandenbindung erforderlich ist. Wir konnten keinen Einfluss der GlyRα1Q177-Varianten auf den Transport des Rezeptors zur Zellmembran feststellen. Allerdings zeigten elektrophysiologische Messungen eine verringerte Wirksamkeit von Glycin, Taurin und β Alanin verglichen mit dem Wildtyp-Protein. Mithilfe von Proteinmodellierung konnte gezeigt werden, dass manche der GlyRα1Q177-Varianten das Wasserstoffbrückennetzwerk im Umfeld von Position Q177 stören. Die größten Effekte wurden bei der Q177R-Variante beobachtet, die sich ähnlich zur Q177K-Mutation der shaky-Maus verhielt. Der Austausch zu einer Aminosäure, die strukturell ähnlich zum ursprünglichen Glutamin ist, störte das Wasserstoffbrückennetzwerk hingegen nicht. Unsere Ergebnisse zeigen, wie wichtig der GlyR β8 β9-Loop für die Aufrechterhaltung der Rezeptorfunktion ist. Sowohl GlyRs als auch GABAARs können durch verschiedenste allosterische Substanzen moduliert werden. Zuletzt zeigten wir positive allosterische Modulation von GABAARs durch Monoteperne aus Pflanzenextrakten. Hier haben wir uns auf den Effekt von 11 Sesquiterpenen und Sesquiterpenoiden (SQTs) auf GABAARs fokussiert. SQTs sind natürlich in Pflanzen vorkommende Stoffe. Wir testeten SQTs aus dem flüchtigen Anteil von Hopfen und Kamille, sowie deren sekundäre Metaboliten, die während der Verdauung entstehen. Mithilfe der Patch-Clamp-Methode konnten wir in transfizierten Zellenlinien und neuronalen Primärzellen signifikante Modulation von GABAARs durch einige der SQTs beobachten. Außerdem wurde mithilfe von Docking-Simulationen eine mögliche Bindung von SQTs in der Neurosteroid-Bindungstasche gezeigt. Zusammengefasst haben wir erfolgreich die Modulation von GABAARs durch SQTs und deren sekundäre Metaboliten demonstriert. Der zweite Teil der vorliegenden Arbeit beschäftigt sich mit dreidimensionalen (3D) in vitro Zellkulturmodellen, die zunehmend an Bedeutung gewinnen. Die dritte Dimension erlaubt die Entwicklungen von komplexen Modellen, die sich der natürlichen Umgebung von Zellen annähern. Dafür werden Materialien benötigt, deren mechanische und biologische Eigenschaften denen des ursprünglichen Gewebes der eingeschlossenen Zellen ähneln. Dies ist insbesondere eine Herausforderung bei 3D in vitro Kulturen von primären Neuronen und Astrozyten, da das Gehirn eines der weichsten Gewebe des Körpers ist. Ultraweiche Matrizen, welche die neuronale Umgebung nachahmen, sind schwer zu handhaben. Wir haben dieses Problem gelöst, indem wir ultraweiches Matrigel mit Fasergerüsten verstärkten, die mithilfe von Melt Electrowriting gedruckt wurden. Somit können diese Matrigel-Faser-Komposite für strukturelle und funktionelle Experimente benutzt werden, die häufige Bewegung und Transport der Proben voraussetzen. Mit diesen Matrigel-Faser-Kompositen haben wir Methoden etabliert, die für die Charakterisierung von neuronalen Netzwerken erforderlich sind. Anstelle von Neuronen haben wir dafür eine Mausfibroblasten-Zelllinie benutzt und mit dem GlyR transfiziert. Zellen in den Matrigel-Faser-Komposite zeigten eine hohe Viabilität, konnten immunocytochemisch angefärbt werden, und mithilfe von elektrophysiologischen Methoden gemessen werden. Darauf aufbauend haben wir primäre kortikale Mausneurone in faserverstärktem Matrigel für bis zu 21 Tage wachsen lassen. Die Neurone zeigten eine hohe Viabilität und durch Quantifikation von Neuritenlänge und Synapsendichte konnte ein vollständig ausgeformtes Netzwerk nach 7 Tagen in 3D-Kultur demonstriert werden. Mithilfe von Calcium-Imaging und Patch-Clamp-Experimenten wurden spontane Netzwerkaktivität, funktionelle spannungsgesteuerte Natriumkanäle, sowie Aktionspotentiale nachgewiesen. Somit konnten wir durch Kombination von einem ultraweichen Hydrogel mit Fasergerüsten erfolgreich ein Zellkulturmodell entwickeln, das zukünftig für die Erforschung von Zell-Zell-Interaktionen zwischen primären Gehirnzellen und Tumorzellen benutzt werden kann. Damit kann die molekulare Pathologie von aggressiven Hirntumoren und möglicherweise anderen Krankheitsmechanismen weiter aufgeklärt werden.

Neste trabalho, são estudados dois dipeptídeos complexados com cobre, Triptofil-Glicina (trp-Gly) e Glicil-Triptofano (Gly-Trp). Focalizamos a interação com o metal de transição, mudanças conformacionais, papel do resíduo pesado de triptofano na simetria dos complexos formados, e explicamos as propriedades espectroscópicas atípicas que observamos no Gly-Trp: Cu+2 em pH´s altos semelhantes aquelas apresentadas em uma espécie de proteínas naturalmente complexadas as proteínas azuis. Para atingirmos tais objetivos, lançamos mão das técnicas de RPE, Dicroísmo Circular (CD) e Absorção ótica, pelas suas complementaridades. Com os dados experimentais, propusemos dois modelos para os complexos com suas funções de onda. Para Trp-Gly: Cu+2, nos pH´s 9,1 e 13,2 e para o Gly-Trp: Cu+2 no pH= 9,1 propomos um modelo que chamamos de covalente. Que consiste basicamente em considerar que os orbitais do íon Cu+2 e seus ligantes, se encontram em simetria quadrado planar (D4h) e que cada ligante no caso nosso, dois oxigênios e dois nitrogênios, tem disponíveis seus orbitais 2s, 2px, 2py, 2pz para a formação dos orbitais moleculares com os orbitais 3d do cobre. As funções assim construídas, dependem de coeficientes que nos dão informações sobre o grau de covalência. O método é semi-empírico. As expressões teóricas dos parâmetros RPE dependem destes parâmetros de covalência e das energias de transição obtidas por absorção ótica no visível. Pudemos então com os valores experimentais das componentes dos tensores g e A obtermos os valores numéricos dos parâmetros de covalência. Para o complexo Gly-Trp: Cu+2, no pH=13,2, propusemos o modele de mistura de orbitais, um modele não covalente que consiste em considerarmos as funções de onda dos estados excitados 4s e 4p do cobre misturadas com as dos orbitais 3d do mesmo íon, para explicar as propriedades espectroscópicas pouco comuns, que se deslocam na direção daquelas obtidas nas proteínas azuis. Conhecendo os valores experimentais das componentes dos tensores g e A, da força de oscilador obtida dos espectros óticos e da força rotacional obtida dos espectros CD, e das auto-funções compatíveis com o modelo, determinamos numericamente os coeficientes de hibridização (mistura). Os parâmetros experimentais, foram determinados através de simulações espectrais, utilizando programas desenvolvidos para este fim. Através deste trabalho, pudemos enfim, verificar a influência do resíduo pesado de triptofano na estereoquímica dos complexos formados, mudanças de simetria, o caráter das ligações, e ate que ponto as propriedades do dipeptídeo Gly- Trp: Cu2+ em pH alto, são semelhantes às proteínas azuis / In this work we studied two dipeptide-copper complexes, being Triptofil-Glycine (Trp-Gly) and Glycil-Triptophan (Gly-Trp). We focused our interest on the interaction with the transition metal, conformational changes and the role that the heavy residue of the Triptophan plays in the symmetry of the complex. Moreover we explain the unusual spectroscopic properties that we observed with Gly-Trp: Cu+2 in high pH solutions similar to that of the so called blue proteins. For these purposes we used such complementary techniques as EPR, Circular Diochrism and Optical Absorption Spectroscopy. Based on our experimental results we proposed two models for the complexes and their wave functions. For the TRP-Gly: Cu+2 in pH of 9.1 and 13.2 and for Gly-Trp: Cu+2 with pH=9.1, we use a model which we call covalent. It consists basically of the consideration that the electronic orbital of the ion Cu+2 and its ligands are in square planar symmetry and that each of the four ligand atoms, in our case two oxygen and two nitrogen atoms, has available 2s, 2px, 2py, 2pz for the formation of molecular orbital with the copper 3d orbital. The wave functions thus constructed depend on coefficients (parameters) that give information on the degree of the covalent character of the bond (complex). The method is semi-empirical. The theoretical expressions for the EPR parameters depend on these coefficients and the transition energies obtained by absorption spectroscopy (in the visible). With the experimental values of the g and A tensors we can therefore obtain numerical values for the covalent coefficients. For the complex Gly-Trp: Cu+2 with pH=13.2 we proposed a model of mixing orbital, a non covalent model that consists of the assumption that the wave functions of the excited states 4s and 4p of the copper mix with the 3d orbital of the same ion. With this model it was possible to explain the uncommon spectroscopic properties that are similar to these of the blue proteins. Knowing the experimental values of the components of the tensors g and A, the oscillator strength obtained by the optical spectra, the rotational strength obtained by the CD spectra and the eigen-functions compatible with the model, we numerically determined the coefficients of hybridization. The experimental parameters were determined by spectral simulations using programs that we developed especially (specifically) for this purpose. Trough this work it was possible to verify the influence of Triptophan on the stereochemistry (stereo chemical behavior) of the formed complexes, on symmetry changes, covalent character and up to which point the properties of the dipeptide Gly-Trp: Cu+2 in high pH are similar to that of the blue protein

Neste trabalho, são estudados dois dipeptídeos complexados com cobre, Triptofil-Glicina (trp-Gly) e Glicil-Triptofano (Gly-Trp). Focalizamos a interação com o metal de transição, mudanças conformacionais, papel do resíduo pesado de triptofano na simetria dos complexos formados, e explicamos as propriedades espectroscópicas atípicas que observamos no Gly-Trp: Cu+2 em pH´s altos semelhantes aquelas apresentadas em uma espécie de proteínas naturalmente complexadas as proteínas azuis. Para atingirmos tais objetivos, lançamos mão das técnicas de RPE, Dicroísmo Circular (CD) e Absorção ótica, pelas suas complementaridades. Com os dados experimentais, propusemos dois modelos para os complexos com suas funções de onda. Para Trp-Gly: Cu+2, nos pH´s 9,1 e 13,2 e para o Gly-Trp: Cu+2 no pH= 9,1 propomos um modelo que chamamos de covalente. Que consiste basicamente em considerar que os orbitais do íon Cu+2 e seus ligantes, se encontram em simetria quadrado planar (D4h) e que cada ligante no caso nosso, dois oxigênios e dois nitrogênios, tem disponíveis seus orbitais 2s, 2px, 2py, 2pz para a formação dos orbitais moleculares com os orbitais 3d do cobre. As funções assim construídas, dependem de coeficientes que nos dão informações sobre o grau de covalência. O método é semi-empírico. As expressões teóricas dos parâmetros RPE dependem destes parâmetros de covalência e das energias de transição obtidas por absorção ótica no visível. Pudemos então com os valores experimentais das componentes dos tensores g e A obtermos os valores numéricos dos parâmetros de covalência. Para o complexo Gly-Trp: Cu+2, no pH=13,2, propusemos o modele de mistura de orbitais, um modele não covalente que consiste em considerarmos as funções de onda dos estados excitados 4s e 4p do cobre misturadas com as dos orbitais 3d do mesmo íon, para explicar as propriedades espectroscópicas pouco comuns, que se deslocam na direção daquelas obtidas nas proteínas azuis. Conhecendo os valores experimentais das componentes dos tensores g e A, da força de oscilador obtida dos espectros óticos e da força rotacional obtida dos espectros CD, e das auto-funções compatíveis com o modelo, determinamos numericamente os coeficientes de hibridização (mistura). Os parâmetros experimentais, foram determinados através de simulações espectrais, utilizando programas desenvolvidos para este fim. Através deste trabalho, pudemos enfim, verificar a influência do resíduo pesado de triptofano na estereoquímica dos complexos formados, mudanças de simetria, o caráter das ligações, e ate que ponto as propriedades do dipeptídeo Gly- Trp: Cu2+ em pH alto, são semelhantes às proteínas azuis / In this work we studied two dipeptide-copper complexes, being Triptofil-Glycine (Trp-Gly) and Glycil-Triptophan (Gly-Trp). We focused our interest on the interaction with the transition metal, conformational changes and the role that the heavy residue of the Triptophan plays in the symmetry of the complex. Moreover we explain the unusual spectroscopic properties that we observed with Gly-Trp: Cu+2 in high pH solutions similar to that of the so called blue proteins. For these purposes we used such complementary techniques as EPR, Circular Diochrism and Optical Absorption Spectroscopy. Based on our experimental results we proposed two models for the complexes and their wave functions. For the TRP-Gly: Cu+2 in pH of 9.1 and 13.2 and for Gly-Trp: Cu+2 with pH=9.1, we use a model which we call covalent. It consists basically of the consideration that the electronic orbital of the ion Cu+2 and its ligands are in square planar symmetry and that each of the four ligand atoms, in our case two oxygen and two nitrogen atoms, has available 2s, 2px, 2py, 2pz for the formation of molecular orbital with the copper 3d orbital. The wave functions thus constructed depend on coefficients (parameters) that give information on the degree of the covalent character of the bond (complex). The method is semi-empirical. The theoretical expressions for the EPR parameters depend on these coefficients and the transition energies obtained by absorption spectroscopy (in the visible). With the experimental values of the g and A tensors we can therefore obtain numerical values for the covalent coefficients. For the complex Gly-Trp: Cu+2 with pH=13.2 we proposed a model of mixing orbital, a non covalent model that consists of the assumption that the wave functions of the excited states 4s and 4p of the copper mix with the 3d orbital of the same ion. With this model it was possible to explain the uncommon spectroscopic properties that are similar to these of the blue proteins. Knowing the experimental values of the components of the tensors g and A, the oscillator strength obtained by the optical spectra, the rotational strength obtained by the CD spectra and the eigen-functions compatible with the model, we numerically determined the coefficients of hybridization. The experimental parameters were determined by spectral simulations using programs that we developed especially (specifically) for this purpose. Trough this work it was possible to verify the influence of Triptophan on the stereochemistry (stereo chemical behavior) of the formed complexes, on symmetry changes, covalent character and up to which point the properties of the dipeptide Gly-Trp: Cu+2 in high pH are similar to that of the blue protein