Crystallization and preliminary structural analysis of the giant haemoglobin from Glossoscolex paulistus at 3.2 angstrom

Glossoscolex paulistus is a free-living earthworm encountered in south-east Brazil. Its oxygen transport requirements are undertaken by a giant extracellular haemoglobin, or erythrocruorin (HbGp), which has an approximate molecular mass of 3.6 MDa and, by analogy with its homologue from Lumbricus terrestris (HbLt), is believed to be composed of a total of 180 polypeptide chains. In the present work the full 3.6 MDa particle in its cyanomet state was purified and crystallized using sodium citrate or PEG8000 as precipitant. The crystals contain one-quarter of the full particle in the asymmetric unit of the I222 cell and have parameters of a = 270.8 angstrom, b = 320.3 angstrom and c = 332.4 angstrom. Diffraction data were collected to 3.15 angstrom using synchrotron radiation on beamline X29A at the Brookhaven National Laboratory and represent the highest resolution data described to date for similar erythrocruorins. The structure was solved by molecular replacement using a search model corresponding to one-twelfth of its homologue from HbLt. This revealed that HbGp belongs to the type I class of erythrocruorins and provided an interpretable initial electron density map in which many features including the haem groups and disulfide bonds could be identified.

Thermal diffusivity of polymers by modified angstrom method

The nature of the molecular structure of plastics makes the properties of such materials markedly temperature dependent. In addition, the continuous increase in the utilization of polymeric materials in many specific applications has demanded knowledge of their physical properties, both during their processing as raw material, as well as over the working temperature range of the final polymer product. Thermal conductivity, thermal diffusivity and specific heat, namely the thermal properties, are the three most important physical properties of a material that are needed for heat transfer calculations. Recently, among several different methods for the determination of the thermal diffusivity and thermal conductivity, transient techniques have become the preferable way for measuring thermal properties of materials. In this work, a very simple and low cost variation of the well known Angstrom method is employed in the experimental determination of the thermal diffusivity of some selected polymers. Cylindrical shaped samples 3 cm diameter and 7 cm high were prepared by cutting from long cylindrical commercial bars. The reproducibility is very good, and the results obtained were checked against results obtained by the hot wire technique, laser flash technique, and when possible, they were also compared with data found in the literature. Thermal conductivity may be then derived from the thermal diffusivity with the knowledge of the bulk density and the specific heat, easily obtained by differential scanning calorimetry. (C) 2009 Elsevier Ltd. All rights reserved.

The 1.1 angstrom resolution crystal structure of [Tyr(15)]EpI, a novel alpha-conotoxin from Conus episcopatus, solved by direct methods

Conotoxins are valuable probes of receptors and ion channels because of their small size and highly selective activity. alpha-Conotoxin EpI, a 16-residue peptide from the mollusk-hunting Conus episcopatus, has the amino acid sequence GCCSDPRCNMNNPDY(SO3H)C-NH2 and appears to be an extremely potent and selective inhibitor of the alpha 3 beta 2 and alpha 3 beta 4 neuronal subtypes of the nicotinic acetylcholine receptor (nAChR). The desulfated form of EpI ([Tyr(15)]EpI) has a potency and selectivity for the nAChR receptor similar to those of EpI. Here we describe the crystal structure of [Tyr(15)]EpI solved at a resolution of 1.1 Angstrom using SnB. The asymmetric unit has a total of 284 non-hydrogen atoms, making this one of the largest structures solved de novo try direct methods. The [Tyr(15)]EpI structure brings to six the number of alpha-conotoxin structures that have been determined to date. Four of these, [Tyr(15)]EpI, PnIA, PnIB, and MII, have an alpha 4/7 cysteine framework and are selective for the neuronal subtype of the nAChR. The structure of [Tyr(15)]EpI has the same backbone fold as the other alpha 4/7-conotoxin structures, supporting the notion that this conotoxin cysteine framework and spacing give rise to a conserved fold. The surface charge distribution of [Tyr(15)]EpI is similar to that of PnIA and PnIB but is likely to be different from that of MII, suggesting that [Tyr(15)]EpI and MII may have different binding modes for the same receptor subtype.

Flexibility revealed by the 1.85 angstrom crystal structure of the beta sliding-clamp subunit of Escherichia coli DNA polymerase III

The beta subunit of the Escherichia coli replicative DNA polymerase III holoenzyme is the sliding clamp that interacts with the alpha (polymerase) subunit to maintain the high processivity of the enzyme. The beta protein is a ring-shaped dimer of 40.6 kDa subunits whose structure has previously been determined at a resolution of 2.5 Angstrom [Kong et al. (1992), Cell, 69, 425-437]. Here, the construction of a new plasmid that directs overproduction of beta to very high levels and a simple procedure for large-scale purification of the protein are described. Crystals grown under slightly modified conditions diffracted to beyond 1.9 Angstrom at 100 K at a synchrotron source. The structure of the beta dimer solved at 1.85 Angstrom resolution shows some differences from that reported previously. In particular, it was possible at this resolution to identify residues that differed in position between the two subunits in the unit cell; side chains of these and some other residues were found to occupy alternate conformations. This suggests that these residues are likely to be relatively mobile in solution. Some implications of this flexibility for the function of beta are discussed.

The 2.0 angstrom crystal structure of a pocilloporin at pH 3.5: The structural basis for the linkage between color transition and halide binding

The pocilloporin Rtms5 and an engineered variant Rtms5(H146S) undergo distinct color transitions (from blue to red to yellow to colorless) in a pH-dependent manner. pK(a) values of 4.1 and 3.2 were determined for the blue (absorption lambda(max), 590 nm) to yellow (absorption lambda(max), similar to 453 nm) transitions of Rtms5 and Rtms5H(146). The pK(a) for the blue-yellow transition of Rtms5H(146S) increased by 1.4 U in the presence of 0.1 M KI, whereas the pK(a) for the same transition of Rtms5 was relatively insensitive to added halides. To understand the structural basis for these observations, we have determined to 2.0 A resolution the crystal structure of a yellow form of Rtms5(H146S) at pH 3.5 in the presence of iodide. Iodide was found occupying a pocket in the structure with a pH of 3.5, forming van der Waals contacts with the tyrosyl moiety of the chromophore. Elsewhere, it was determined that this pocket is occupied by a water molecule in the Rtms5(H141S) structure (pH 8.0) and by the side chain of histidine 146 in the wild-type Rtms5 structure. Collectively, our data provide an explanation for the observed linkage between color transitions for Rtms5(H146S) and binding to halides.

Crystal structure at 1.1 angstrom resolution of alpha-conotoxin PnIB: Comparison with alpha-conotoxins PnIA and GI

Conotoxins are small, cysteine-rich peptides isolated from the venom of Conus spp. of predatory marine snails, which selectively target specific receptors and ion channels critical to the functioning of the neuromuscular system. alpha-Conotoxins PnIA and PnIB are both 16-residue peptides (differing in sequence at only two positions) isolated from the molluscivorous snail Conus pennaceus. In contrast to the muscle-selective alpha-conotoxin GI from Conus geographus, PnIA and PnIB block the neuronal nicotinic acetylcholine receptor (nAChR). Here, we describe the crystal structure of PnIB, solved at a resolution of 1.1 Angstrom and phased using the Shake-and-Bake direct methods program. PnIB crystals are orthorhombic and belong to the space group P2(1)2(1)2(1) with the following unit cell dimensions: a = 14.6 Angstrom, b = 26.1 Angstrom, and c = 29.2 Angstrom. The final refined structure of alpha-conotoxin PnIB includes all 16 residues plus 23 solvent molecules and has an overall R-factor of 14.7% (R-free of 15.9%). The crystal structures of the alpha-conotoxins PnIB and PnIA are solved from different crystal forms, with different solvent contents. Comparison of the structures reveals them to be very similar, showing that the unique backbone and disulfide architecture is not strongly influenced by crystal lattice constraints or solvent interactions. This finding supports the notion that this structural scaffold is a rigid support for the presentation of important functional groups. The structures of PnIB and PnIA differ in their shape and surface charge distribution from that of GI.

Structure of CcmG/DsbE at 1.14 angstrom resolution: High-fidelity reducing activity in an indiscriminately oxidizing environment

CcmG is unlike other periplasmic thioredoxin (TRX)like proteins in that it has a specific reducing activity in an oxidizing environment and a high fidelity of interaction. These two unusual properties are required for its role in c-type cytochrome maturation. The crystal structure of CcmG reveals a modified TRX fold with an unusually acidic active site and a groove formed from two inserts in the fold. Deletion of one of the groove-forming inserts disrupts c-type cytochrome formation. Two unique structural features of CcmG-an acidic active site and an adjacent groove-appear to be necessary to convert an indiscriminately binding scaffold, the TRX fold, into a highly specific redox protein.

Modelo de gest??o do ambiente de TI aplicado ao IBGE

A arquitetura de inform??tica do IBGE busca refletir a evolu????o das Tecnologias da Informa????o e de Comunica????o (TIC) e vem sendo modificada ao longo dos anos, de maneira a manter - se um equil??brio entre os anseios e diretrizes institucionais e governamentais. A partir do aprendizado e do sucesso obtidos no Censo Demogr??fico 2010, o IBGE inova agora na forma de administrar sua ??rea de TIC, baseado em software especialista adquirido.O IBGE se beneficia da administra????o dos bens de inform??tica, da responsabilidade sobre contratos, da gest??o do patrim??nio, do uso otimizado dos softwares comerciais, da agilidade de obten????o de informa????es sobre o parque computacional instalado, do monitoramento on-line dos servi??os oferecidos pela TI, da economia de gastos com viagens para suporte t??cnico dentro dos estados e entre os mesmos, da reeduca????o de funcion??rios quanto ao uso de tecnologias, da forma organizada e planejada de trabalho e, portanto, da gest??o p??blica das TIC

Modelo de gest??o de capacita????o da Presid??ncia da Rep??blica: pool de capacita????o

A fun????o capacita????o passa a ser concebida dentro de uma nova proposta materializada no modelo Pool de Capacita????o que tem por objetivos aumentar a capacidade do processo, alinhar a ??rea de recursos humanos ??s estrat??gias institucionais e sintoniz??-la com a cultura organizacional e os cen??rios externos. O processo de capacita????o passa a operar de forma sist??mica, desconcentrada e articulada em rede interna e externa

Condom??nio de empregadores rurais: um novo modelo de contrata????o no meio rural

O Minist??rio do Trabalho e Emprego, por interm??dio de sua Secretaria de Inspe????o do Trabalho, vem desenvolvendo arrojado programa de metas, visando diminuir os altos ??ndices de informalidade na contrata????o de m??o-de-obra. Al??m de ilegal, tal situa????o provoca graves preju??zos aos trabalhadores. Visando superar este contexto no meio rural, a Secretaria de Inspe????o do Trabalho lan??ou o projeto denominado "Condom??nio de Empregadores". O Condom??nio de Empregadores ?? a uni??o de produtores rurais pessoas f??sicas, com a ??nica finalidade de contratar diretamente empregados rurais, sendo outorgados a um dos produtores poderes para contratar e gerir a m??o-de-obra em suas propriedades. Iniciado em julho de 1999, o projeto consiste na capacita????o dos auditores fiscais, no estabelecimento de parcerias com institui????es governamentais e n??o governamentais e na implanta????o desse novo modelo de contrata????o em ??mbito nacional. Com o apoio do Minist??rio P??blico do Trabalho, do Instituto Nacional de Seguridade Social e de entidades representativas dos trabalhadores e segmento patronal, j?? foram implantados condom??nios no Paran??, Minas Gerais e S??o Paulo. Espera-se at?? o final do ano a cria????o de condom??nios em quase todo o territ??rio nacional, com a regulariza????o de dezenas de milhares de v??nculos laborais

O impacto do modelo gerencial na Administra????o P??blica: um breve estudo sobre a experi??ncia internacional recente

Texto que focaliza o processo de surgimento e desenvolvimento do modelo gerencial (managerialism ou public management) no campo da administra????o p??blica, analisando seus limites e potencialidades, mediante a abordagem do caso ingl??s e americano de reformas administrativas de governo, ao longo das d??cadas de 80 e 90; ao final, al??m do perfil das principais mudan??as administrativas que t??m afetado o setor p??blico em escala mundial, um coment??rio breve sobre o caso brasileiro.

A jornada da aprendizagem: um guia para alcan??ar a excel??ncia; Um modelo canadense de administra????o p??blica?

Este Caderno traz dois relat??rios de pesquisa internacionais. O primeiro objetiva fazer um levantamento do que se sabe sobre organiza????es de aprendizagem, traduzir as informa????es resultantes em orienta????es pr??ticas e desenvolver abordagens que possam ajudar gerentes a transformar seus locais de trabalho. O segundo relat??rio objetiva verificar a exist??ncia de um modelo canadense de administra????o p??blica canadense, identificando suas principais caracter??sticas distintivas de outros modelos

Texto para discuss??o 35: modelo para informatiza????o das administra????es p??blicas municipais

O presente trabalho ?? resultado de um estudo onde observamos planos diretores de inform??tica e, considerando sua l??gica, verificamos que eles, na forma como s??o propostos para empresas do setor privado, n??o se aplicam ao setor p??blico

Texto para discuss??o 40: entre o p??blico e o privado: o modelo de gest??o de res??duos s??lidos adotados pela SLU de Belo Horizonte

O estudo empreende uma an??lise do programa de gera????o de renda e emprego embutido no modelo de gest??o de res??duos s??lidos da SLU de Belo Horizonte, focalizando os mecanismos de gest??o adotados e enunciando os principais problemas enfrentados pelos agentes envolvidos no processo. O trabalho procura explicitar o marco de refer??ncia utilizado para embasar a reflex??o do modelo de gest??o de res??duos s??lidos. Posteriormente, ?? apresentada a metodologia empregada. Na seq????ncia, encontra-se a descri????o propriamente dita do modelo de gest??o de res??duos s??lidos da SLU de Belo Horizonte, bem como dos seus impactos no que diz respeito ?? gera????o de emprego e renda, o que significa incluir a ASMARE como o outro p??lo da parceria. Aqui estar??o expostos os resultados relevantes da pesquisa, bem como a an??lise dos resultados e os coment??rios conclusivos encerrando a an??lise