Dissociation constants for alternate dirmcleotide substrates and competitive inhibitors suggest that the dinucleotide binding site of the Ascaris suum NAD-malic enzyme is hydrophobic in the vicinity of the nicotinamide ring. Changes in the divalent metal ion activator from Mg^2+ to Mn^2+ or Cd^2+ results in a decrease in the dinucleotide affinity and an increase in the affinity for malate. Primary deuterium and 13-C isotope effects obtained with the different metal ions suggest either a change in the transition state structure for the hydride transfer or decarboxylation steps or both. Deuterium isotope effects are finite whether reactants are maintained at saturating or limiting concentrations with all the metal ions and dinucleotide substrates used. With Cd^2+ as the divalent metal ion, inactivation of the enzyme occurs whether enzyme alone is present or is turning over. Upon inactivation only Cd^2+ ions are bound to the enzyme which becomes denatured. Modification of the enzyme to give an SCN-enzyme decreases the ability of Cd^2+ to cause inactivation. The modified enzyme generally exhibits increases in K_NAD and K_i_metai and decreases in V_max as the metal size increases from Mg^2+ to Mn^2+ or Cd^2+, indicative of crowding in the site. In all cases, affinity for malate greatly decreases, suggesting that malate does not bind optimally to the modified enzyme. For the native enzyme, primary deuterium isotope effects increase with a concomitant decrease in the 13-C effects when NAD is replaced by an alternate dinucleotide substrate different in redox potential. This suggests that when the alternate dinucleotides are used, a switch in the rate limitation of the chemical steps occurs with hydride transfer more rate limiting than decarboxylation. Deuteration of malate decreases the 13-C effect with NAD for the native enzyme, but an increase in 13-C effect is obtained with alternate dinucleotides. These suggest the presence of a secondary 13-C effect in the hydride transfer step. This phenomenon is also applicable to the modified enzyme with NAD as the substrate.

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Submitted by (edna.saturno@ufrpe.br) on 2016-07-28T12:35:54Z No. of bitstreams: 1 Alessandra Santos Alencar.pdf: 4687289 bytes, checksum: 69f920d7a8dc062fcb65629d8888441f (MD5) / Made available in DSpace on 2016-07-28T12:35:54Z (GMT). No. of bitstreams: 1 Alessandra Santos Alencar.pdf: 4687289 bytes, checksum: 69f920d7a8dc062fcb65629d8888441f (MD5) Previous issue date: 2010-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Researchers and veterinarians who work in swine production in Brazil have a good idea of existing health problems, especially in your own area of expertise. Due to the short production cycle and the clinical or subclinical character in many of the diseases that affect pigs, there was the possibility of using the slaughterhouse as an important source of epidemiological data on the incidence and prevalence of disease in flocks, making the monitoring of animals in slaughter houses one of the most important sources of information to obtain data to assess the health situation of production systems for pigs with the aim of obtaining statistics on incidence or prevalence of limiting diseases affecting pigs. Thus, this work was developed to analyze the association between the frequency of infection with helminths and coccidia and property characteristics, and evaluate lesions in organs of pigs in slaughterhouses of the metropolitan area of Recife and of the (“Zona da Mata”) of Pernambuco, Brazil. The work was done in three slaughterhouses of the inspection system state, located in the metropolitan area of Recife and in the (“Zona da Mata”) of Pernambuco state, from July 2008 to May 2009. A total of 715 pigs were analyzed, from eight industrial farms and three of subsistence. The count of eggs / oocysts in the feces was calculated and larval culture for diagnosis of infection by gastrointestinal parasites in fecal samples was performed. Inspection of the viscera for examination of lesions and collection of material for histopathological examination were carried out. A questionnaire was used to ascertain the situation of the farms. The positivity for helminths was 2.7%(12/447), predominantly Strongyloidea type eggs. The presence ofoocysts was detected in 6.5% (29/447),including Eimeria spp and Isospora suis. The gross lesions predominated in lung with 43.8% (313/715), followed by 4.7% (35/715) for liver and kidneys with 2.6% (19/715), with higher frequencies respectively for pneumonia, milk spots and hydronephrosis. Histopathologically, granulomatous pneumonia predominated; in the livers with milk spots it was observed sinusoidal congestion, granulomatous inflammatory foci, peri-granulomatous hepatitis, and eosinophilic infiltration in the interlobular spaces, and in kidney, chronic interstitial nephritis. There was a significant association (p <0.05) with the variables related to management of facilities, particularly sanitary aspects, both the rates of parasitism by helminths and coccidia as to the frequency of milk spots and lung lesions. / Os pesquisadores e veterinários que atuam na suinocultura brasileira possuem uma boa idéia dos problemas sanitários existentes, especialmente na sua própria região de atuação. Em função do curto ciclo de produção e do caráter clínico ou subclínico de muitas das enfermidades que acometem os suínos, a utilização do matadouro surgiu como importante fonte de dados epidemiológicos sobre a incidência e prevalência de doenças nos rebanhos, tornando-se a monitoria de animais em abatedouros uma das mais importantes fontes de informações para a obtenção de dados para avaliação da situação da saúde de sistemas de produção de suínos, com a finalidade de obter estatística sobre incidências ou prevalências de doenças limitantes que afetam os suínos. Desta forma, desenvolveu-se este trabalho com o objetivo de analisar a associação entre a frequência de infecção por helmintos e coccídios e características das propriedades, e avaliar as lesões em órgãos de suínos em abatedouros da Região Metropolitana de Recife e Zona da Mata do estado de Pernambuco, Brazil. O trabalho foi realizado em três abatedouros inscritos no sistema de inspeção estadual, localizados na Região Metropolitana de Recife e Zona da Mata do estado Pernambuco, no período de julho de 2008 a maio de 2009. Analisaram-se 715 suínos, oriundos de oito granjas tecnificadas e três de subsistência. Realizou-se a contagem de ovos/oocistos nas fezes e coprocultura para diagnóstico da infecção por parasitos gastrintestinais em amostras fecais coletadas na linha de inspeção, além da inspeção das vísceras para verificação de lesões e coleta de material para exame histopatológico. Um questionário investigativo foi utilizado para conhecer a situaçãodas granjas. A positividade para helmintos foi de 2,7% (12/447), predominando ovos tipo Strongyloidea. A presença de coccídios foi detectada em 6,5% (29/447), incluindo Eimeria spp e Isospora suis. Dentre os achados macroscópicos predominaram as de pulmão com 43,8% (313/715), seguidas de 4,7% (35/715) para fígado e rins com 2,6% (19/715), com frequências respectivamente maiores para pneumonia, manchas leitosas e hidronefrose. Histologicamente, predominaram as pneumonias granulomatosas; nos fígados com manchas leitosas foram observados congestão sinusoidal, focos inflamatórios granulomatosos, perihepatite granulomatosa, e infiltração eosinofílica nos espaços interlobulares. Nos rins, nefrite intersticial crônica. Observou-se associação significativa (p < 0,05) com as variáveis relacionadas ao manejo das instalações, particularmente os aspectos higiênicos, tanto para as taxas de parasitismo por helmintos e coccídios quanto para a frequências de manchas leitosas e lesões pulmonares