Metal dependence of the nonplanar distortion of octaalkyltetraphenylporphyrins

Sparks, Laurie D.; Medforth, Craig J.; Park, M. S.; Chamberlain, J.R.; Ondrias, M. R.; Senge, Ma­thias O.; Smith, Kevin M.; Shelnutt, John A.

doi:10.1021/ja00055a030

Cited by 258 publications

(270 citation statements)

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“…54,89,90 However, the discovery via resonance Raman (RR) spectroscopy by Shelnutt and coworkers that the conformational flexibility of Ni(II)OEP 21 observed amongst the various crystal forms (Fig. 8) was also present in solution deserves special mention, in particular that the non-planar form displayed red-shifted absorptions, which is a characteristic marker of non-planarity.…”

Section: 88mentioning

confidence: 99%

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Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

2015

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Tetrapyrrole-containing proteins are one of the most fundamental classes of enzymes in nature and it remains an open question to give a chemical rationale for the multitude of biological reactions that can be catalyzed by these pigmentprotein complexes. There are many fundamental processes where the same (i.e., chemically identical) porphyrin cofactor is involved in chemically quite distinct reactions. For example, heme is the active cofactor for oxygen transport and storage (hemoglobin, myoglobin) and for the incorporation of molecular oxygen in organic substrates (cytochrome P 450 ). It is involved in the terminal oxidation (cytochrome c oxidase) and the metabolism of H 2 O 2 (catalases and peroxidases) and catalyzes various electron transfer reactions in cytochromes. Likewise, in photosynthesis the same chlorophyll cofactor may function as a reaction center pigment (charge separation) or as an accessory pigment (exciton transfer) in light harvesting complexes (e.g., chlorophyll a). Whilst differences in the apoprotein sequences alone cannot explain the often drastic differences in physicochemical properties encountered for the same cofactor in diverse protein complexes, a critical factor for all biological functions must be the close structural interplay between bound cofactors and the respective apoprotein in addition to factors such as hydrogen bonding or electronic effects. Here, we explore how nature can use the same chemical molecule as a cofactor for chemically distinct reactions using the concept of conformational flexibility of tetrapyrroles. The multifaceted roles of tetrapyrroles are discussed in the context of the current knowledge on distorted porphyrins. Contemporary analytical methods now allow a more quantitative look at cofactors in protein complexes and the development of the field is illustrated by case studies on hemeproteins and photosynthetic complexes. Specific tetrapyrrole conformations are now used to prepare bioengineered designer proteins with specific catalytic or photochemical properties.

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Section: 88mentioning

confidence: 99%

“…90 The macrocycle distortive effects of peripheral steric strain could even be 'prevented' with sufficiently large metal ions.…”

Section: 100mentioning

confidence: 99%

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

2015

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“…Therefore, as ex-further due to synthetic difficulties in the preparation of longer chain pyrrole diacetic esters. pected, [22] complexation with zinc ion significantly reduces the activation energy for the ring inversion process in H 2 C 10 OAP and ZnC 10 OAP were examined at their room-temperature and high-temperature phases by powder these porphyrins.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Mesogenic Properties of Porphyrin Octaesters

et al. 1999

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A new and efficient method of preparing 3,4‐pyrrolediacetic esters 3 is reported, together with their conversion, according to the Lindsey procedure, to a series of octa‐ and dodeca‐substituted porphyrins. This procedure, which consists of a palladium‐catalysed oxidative alkoxycarbonylation of N‐substituted dipropargylamine derivatives 1, works nicely for n‐alkyl alcohols in the range C1 to C14. The thermotropic behaviour of this series of porphyrins (28 compounds) has been investigated using polarization microscopy, DSC, X‐ray diffraction, and miscibility tests. The planarity of the macrocyclic core constitutes the major structural requirement for mesophase formation. The mesophase temperature range is controlled by the length of the side chains through the melting point and by the strength of π‐π interactions among the cores through the clearing point. The same set of rules governing porphyrin packing in the solid state can be employed to predict mesophase formation and organization in porphyrin octaesters

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“…No entanto, os substituintes corretos necessitam ser incluídos para se produzir cálculos com boa concordância com as tendências espectrais, pois se empregando uma porfirina de geometria incorreta os cálculos de orbitais moleculares, mesmo com os substituintes corretos, proporcionam uma pobre concordância com o espectro de absorção. 19,198 CONCLUSÕES Segundo Vinogradov, 4 as hemoglobinas extracelulares gigantes constituem o ápice de complexidade em hemoproteínas. A opinião deste expert na área merece nossa corroboração.…”

Section: A Configuração Eletrônica Dos Grupos Heme Férricos Para Os Sunclassified

Hemoglobina extracelular gigante de Glossoscolex paulistus: um extraordinário sistema supramolecular hemoproteico

et al. 2011

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Recebido em 26/1/10; aceito em 1/6/10; publicado na web em 22/9/10 GIANT EXTRACELLULAR HEMOGLOBIN OF Glossoscolex paulistus: AN EXTRAORDINARY SUPRAMOLECULAR HEMOPROTEIN SYSTEM. Giant extracellular hemoglobins are considered the summit of complexity in systems that carry oxygen, constituting an extraordinary model system to the study of hemoproteins. This class includes the hemoglobin of the annelid Glossoscolex paulistus that presents high cooperativity, great oligomeric and redox stabilities and ability of oligomeric reassociation. These properties have motivated evaluations about its utilization as prototype of artificial blood and biosensor. Kinetic studies involving autoxidation and detailed spectroscopic characterizations of its ferrous and ferric species have propitiated information about the structure-activity relationship of this macromolecule. The present review analyzes several biochemical issues, evaluating the state-of-art of this subject.Keywords: hemoglobin; ligand exchange; autoxidation. INTRODUÇÃOA hemoglobina extracelular gigante de Glossoscolex paulistus (HbGp) é uma hemoproteína que constitui um sistema carregador de oxigênio in vivo e, consequentemente, credenciado pela seleção natural, apresentando características extremamente interessantes em termos de evolução como, por exemplo, sua possível adaptação a meios ricos em sulfetos.1 Esta hemeproteína apresenta uma extraordinária massa molecular, em torno de 3,1 MDa, 2 com uma unidade estrutural básica altamente organizada, contendo 144 cadeias que apresentam o grupo heme, além da presença de aproximadamente 36 cadeias que não apresentam este grupamento prostético.Os sistemas hemoglobínicos gigantes extracelulares, também conhecidos por eritrocruorinas, 3 constituem arranjos supramoleculares proteicos tão elaborados do ponto de vista da sua relação estrutura/ atividade, que são considerados, segundo Vinogradov, 4,5 o ápice de complexidade em se tratando de hemoproteínas que ligam oxigênio.Além disso, este grupo de hemoglobinas é conhecido por ligações de oxigênio altamente cooperativas.6-8 Entre elas, destaca-se a hemoglobina de Lumbricus terrestris, que vem sendo amplamente estudada por diversos grupos e que apresenta similaridade macromolecular com a hemoglobina de Glossoscolex paulistus. Cálculos por homologia envolvendo o monômero d de Glossoscolex paulistus constataram uma identidade estrutural de 54% em relação ao monômero d de Lumbricus terrestris.A título de ilustração, é interessante mencionar que a hemoglobina de Lumbricus terrestris vem sendo aplicada em pesquisas sobre sangue artifical, 7,9,10 devido à sua natureza extracelular, grande tamanho e resistência à oxidação. Em relação a este último tópico, vale citar os trabalhos de Dorman e colaboradores 9 e Madura e colaboradores 8 que, por meio de estudos espectroeletroquímicos, têm determinado que a hemoglobina de Lumbricus terrestris exibe potenciais redox altamente positivos (de +112 até +61 mV) quando comparados aos potenciais negativos das hemoglobinas tetraméricas e mioglobinas ...

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Metal dependence of the nonplanar distortion of octaalkyltetraphenylporphyrins

Cited by 258 publications

References 2 publications

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

Conformational control of cofactors in nature – the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles

Synthesis and Mesogenic Properties of Porphyrin Octaesters

Hemoglobina extracelular gigante de Glossoscolex paulistus: um extraordinário sistema supramolecular hemoproteico

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