RESUMO
CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.
RESUMO
This study characterizes the calcium-bound CR I-II domain (residues 1-100) of rat calretinin (CR). CR, with six EF-hand motifs, is believed to function as a neuronal intracellular calcium-buffer and/or calcium-sensor. The secondary structure of CR I-II, defined by standard NMR methods on 13C,15N-labeled protein, contains four helices and two short interacting segments of extended structure between the calcium-binding loops. The linker between the two helix-loop-helix, EF-hand motifs is 12 residues long. Limited trypsinolysis at K60 (there are 10 other K/R residues in CR I-II) confirms that the linker of CR I-II is solvent-exposed and that other potential sites are protected by regular secondary structure. 45Ca-overlay of glutathione S-transferase (GST)-CR(1-60) and GST-CR(61-100) fusion proteins confirm that both EF-hands of CR I-II have intrinsic calcium-binding properties. The primary sequence and NMR chemical shifts, including calcium-sensitive glycine residues, also suggest that both EF-hand loops of CR I-II bind calcium. NMR relaxation, analytical ultracentrifugation, chemical cross-linking and NMR translation diffusion measurements indicate that CR I-II exists as a monomer. Calb I-II (the homologous domain of calbindin D28k) has the same EF-hand secondary structures as CR I-II, except that helix B is three residues longer and the linker has only four residues [Klaus, W., Grzesiek, S., Labhardt, A. M., Buckwald, P., Hunziker, W., Gross, M. D. & Kallick, D. A. (1999) Eur. J. Biochem. 262, 933-938]. In contrast, Calb I-II binds one calcium cation per monomeric unit and exists as a dimer. Despite close homology and similar secondary structures, CR I-II and Calb I-II probably have distinct tertiary structure features that suggest different cellular functions for the full-length proteins.
Assuntos
Proteínas do Tecido Nervoso/química , Proteína G de Ligação ao Cálcio S100/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Calbindina 1 , Calbindina 2 , Calbindinas , Cálcio/metabolismo , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/química , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Ratos , Proteína G de Ligação ao Cálcio S100/genética , Proteína G de Ligação ao Cálcio S100/metabolismo , Homologia de Sequência de AminoácidosRESUMO
Blood methemoglobin levels and blood cell counts were carried out in 64 children of the State Children's Home is Gdansk-Oliwa. An excessive consumption of nitrites and nitrites leading to the increase in methemoglobinemia and anaemia observe in the previous studies stimulated the present investigations. Methemoglobinemia was detected in 14.1% of children together with marked anaemia especially in the youngest children. The authors suggest that partial elimination of nitrites and nitrates from the diet and periodical analysis of the drinking water and food seem necessary.
