RESUMO
The hydroxamate siderophores putrebactin, desferrioxamine B, and desferrioxamine E bind Mn(II) and promote the air oxidation of Mn(II) to Mn(III) at pH>7.1. The magnetic susceptibility of the manganese complexes were determined by the Evans method and the stoichiometry was probed with electrospray ionization mass spectrometry (ESIMS). The room temperature magnetic moments (µeff) for the manganese complexes of desferrioxamines B and E were 4.85 BM and 4.84 BM, respectively, consistent with a high spin, d(4), Mn(III) electronic configuration. The manganese complex of putrebactin had a magnetic moment of 4.98 BM, consistent with incomplete oxidation of Mn(II), as confirmed by X band EPR spectroscopy. Mass spectra of the Mn(III) desferrioxamine B and E complexes showed complexes at m/z 613.26 and 653.26, respectively, consistent with 1:1 complexation. Mass spectral peaks for manganese putrebactin at m/z 797.31 and 1221.41 corresponds to 1:2 and 2:3 Mn:putrebactin complexation. This study directly confirms the Mn(III) oxidation state in hydroxamate siderophore complexes.
Assuntos
Complexos de Coordenação/química , Ácidos Hidroxâmicos/química , Manganês/química , Sideróforos/química , Complexos de Coordenação/metabolismo , Desferroxamina/química , Desferroxamina/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Ácidos Hidroxâmicos/metabolismo , Lactamas/química , Lactamas/metabolismo , Espectroscopia de Ressonância Magnética , Magnetismo , Manganês/metabolismo , Estrutura Molecular , Oxirredução , Putrescina/análogos & derivados , Putrescina/química , Putrescina/metabolismo , Sideróforos/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria , Succinatos/química , Succinatos/metabolismoRESUMO
The Deepwater Horizon oil spill in 2010 released an unprecedented amount of oil into the ocean waters of the Gulf of Mexico. As a consequence, bioremediation by oil-degrading microbes has been a topic of increased focus. One factor limiting the rate of hydrocarbon degradation by microbial communities is the availability of necessary nutrients, including iron. The siderophores produced from two Vibrio spp. isolated from the Gulf of Mexico following the Deepwater Horizon oil spill, along with the well-studied oil-degrading microbe, Alcanivorax borkumensis SK2, are studied under iron-limiting conditions. Here we report the amphiphilic amphibactin siderophores produced by the oil-associated bacteria, Vibrio sp. S1B, Vibrio sp. S2A and Alcanivorax borkumensis SK2. These findings provide insight into oil-associating microbial iron acquisition.
Assuntos
Alcanivoraceae/metabolismo , Sideróforos/metabolismo , Vibrio/metabolismo , Alcanivoraceae/genética , Biodegradação Ambiental , Vias Biossintéticas , Genes Bacterianos , Hidrocarbonetos/metabolismo , Poluição por Petróleo/análise , Análise de Sequência de DNA , Sideróforos/genética , Vibrio/genéticaRESUMO
Early investigations of guilt cast it as an emotion that prompts broad reparative behaviors that help guilty individuals feel better about themselves or about their transgressions. The current investigation found support for a more recent representation of guilt as an emotion designed to identify and correct specific social offenses. Across five experiments, guilt influenced behavior in a targeted and strategic way. Guilt prompted participants to share resources more generously with others, but only did so when those others were persons whom the participant had wronged and only when those wronged individuals could notice the gesture. Rather than trigger broad reparative behaviors that remediate one's general reputation or self-perception, guilt triggers targeted behaviors intended to remediate specific social transgressions.
