RESUMO
Tobacco smoke contains various cancer-causing toxic substances, including nicotine and nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN). The cytochrome 2A13 is involved in nicotine metabolism and in the activation of the pro-carcinogenic agents NNK and NNN, by means of α-hydroxylation reactions. Despite the significance of cytochrome 2A13 in the biotransformation of these molecules, its conformational mechanism and the molecular basis involved in the process are not fully understood. In this study, we used molecular dynamics and principal component analysis simulations for an in-depth analysis of the essential protein motions involved in the interaction of cytochrome 2A13 with its substrates. We also evaluated the interaction of these substrates with the amino acid residues in the binding pocket of cytochrome 2A13. Furthermore, we quantified the nature of these chemical interactions from free energy calculations using the Molecular Mechanics/Generalized Born Surface Area method. The ligands remained favorably oriented toward compound I (cytochrome P450 OâFeIV state), to undergo α-hydroxylation. The hydrogen bond with asparagine 297 was essential to maintaining the substrates in a favorable catalytic orientation. The plot of first principal motion vs second principal motion revealed that the enzyme's interaction with nicotine and NNK involved different conformational subgroups, whereas the conformational subgroups in the interaction with NNN are more similar. These results provide new mechanistic insights into the mode of interaction of the substrates with the active site of cytochrome 2A13, in the presence of compound I, which is essential for α-hydroxylation.
Assuntos
Hidrocarboneto de Aril Hidroxilases/metabolismo , Simulação de Dinâmica Molecular , Nicotina/metabolismo , Nitrosaminas/metabolismo , Hidrocarboneto de Aril Hidroxilases/química , Biocatálise , Domínio Catalítico , Simulação de Acoplamento MolecularRESUMO
The objective of this study was to investigate whether the different time of collection of nectar in hive areas influence the volume, the concentration of sugar and total amount of sugar produced by all its flowers at the time of anthesis, as well as evaluating possible changes in the characteristics of nectar along the time and discuss the beekeeping potential of areas containing jitirana-branca (Merremia aegyptia). It was also evaluated the relationship between the generation of floral attractive and the behavior of potential pollinators, including Apis mellifera L. (Africanized honeybee). The study was conducted in a preservation area of Caatinga, at the campus of FATEC, Quixeramobim, CE, Brazil. It was found that: the mean floral density of M. aegyptia was 33.7 flowers/m2; the volume of nectar was affected by the time of collection and no more nectar is secreted by the flowers after 11:00 AM. Keywords: Sugars, Caatinga, Merremia aegyptia, Africanized honeybee.
O objetivo deste trabalho foi o de investigar se os diferentes horários de coleta de néctar em áreas apícolas influenciam no volume, concentração de açúcar e açúcar total produzido por suas flores, no momento da antese, bem como verificar possíveis alterações nas características do néctar ao longo do tempo e discutir as conseqüências no potencial apícola das áreas de jitirana-branca (Merremia aegyptia). Também foi avaliada a relação entre esta produção de atrativos florais e o comportamento dos polinizadores potenciais, dentre estes a Apis mellifera L. (abelha africanizada). A pesquisa foi realizada em uma área de preservação de Caatinga, no Campus da FATEC Sertão Central, Quixeramobim, Ceará. Foi constatado que: a densidade floral média foi 33,7 flores/m²; seu volume de néctar variou de acordo com o horário de coleta e não há reposição de néctar na flor após as 11:00 horas. Palavras-Chave: Açúcares, Caatinga, jitirana branca, abelha africanizada.
RESUMO
This work aimed to perform a survey of the species of aboriginal bees without sting created by stingless bees keepers in Rio Grande do Norte state, Brazil, as well to do a study on its geographic distribution in the state. The research was directed to 104 stingless bees keepers in cities where it had greater concentration of creators of aboriginal bees in Rio Grande do Norte state, Brazil. The species of stingless bees of 104 stingless bees keepers distributed in 29 cities of the state had been investigated. It evidenced that the bee without sting M. subnitida, with 86% of frequency, is the stingless bees species with better geographic distribution in the Rio Grande do Norte state, predominating in all the visited keepers. The P. mosquito specie presented frequency of 4.9%. The presence of this species was not evidenced in all the studied areas, the same occurred with species M. asilvae with 4.3% of frequency, M. scutellaris with a frequency of 1.4%, and P. cupira, Frieseomelitta spp and F. varia, that together they had answered with frequency of 3.4% in all state. Keywords: Beekeeping of stingless bees, jandaíra, uruçu, mosquito, rajada.
Este trabalho teve por objetivo realizar um levantamento das espécies de abelhas indígenas sem ferrão criadas em meliponários no estado do Rio Grande do Norte, bem como fazer um estudo sobre sua distribuição geográfica no estado. A pesquisa foi dimensionada a 104 meliponicultores em cidades onde se sabia haver maior concentração de criadores de abelhas indígenas no estado do Rio Grande do Norte. Foram investigadas as espécies de abelhas sem ferrão de 104 meliponários distribuídos em 29 municípios do território potiguar. Constatou-se que a abelha sem ferrão M. subnitida, com uma freqüência de 86%, é a espécie meliponínea com melhor distribuição geográfica no estado do Rio Grande do Norte, predominando em todos os meliponários visitados. A espécie P. mosquito respondeu pela freqüência de 4,9%. A presença desta espécie não foi constatada em todas as áreas estudadas, o mesmo ocorreu com as espécies M. asilvae com uma freqüência de 4,3%, M. scutellaris com uma freqüência de 1,4% e P. cupira, Frieseomelitta spp e F. varia, que juntas responderam pela freqüência de 3,4% em todo estado. Palavras-Chave: Meliponicultura, jandaíra, uruçu, mosquito, rajada.