Selenium in Proteins: Conformational Changes Induced by Se Substitution on Methionine, as Studied in Isolated Model Peptides by Optical Spectroscopy and Quantum Chemistry.

The side-chain of methionine residues is long enough to establish NH⋯S H-bonds with neighboring carbonyl groups of the backbone, giving rise to so-called intra-residue 6δ and inter-residue 7δ H-bonds. The aim of the present article is to document how the substitution of sulfur with a selenium atom affects the H-bonding of the Met system. This was investigated both experimentally and theoretically by conformation-resolved optical spectroscopy, following an isolated molecule approach. The present work emphasizes the similarities of the Met and Sem residues in terms of conformational structures, energetics, NH⋯Se/S H-bond strength and NH stretch spectral shifts, but also reveals subtle behavior differences between them. It provides evidence for the sensitivity of the H-bonding network with the folding type of the Sem/Met side-chains, where a simple flip of the terminal part of the side-chain can induce an extra 50 cm-1 spectral shift of the NH stretch engaged in a 7δ NH⋯S/Se bond.

The Effects of Seleno-Methionine in Cadmium-Challenged Human Primary Chondrocytes.

Cadmium (Cd) is a potentially toxic element able to interfere with cellular functions and lead to disease or even death. Cd accumulation has been demonstrated in cartilage, where it can induce damage in joints. The aim of this study was to evaluate the effect of CdCl2 on primary cultures of human chondrocytes and the possible protective effect of seleno-methionine (Se-Met). Human primary articular chondrocytes were cultured and treated as follows: control groups, cells challenged with 7.5 µM and 10 µM CdCl2 alone, and cells pretreated with 10 and 20 µM Se-Met and then challenged with 7.5 µM and 10 µM CdCl2. Twenty-four hours after incubation, cell viability, histological evaluation with hematoxylin-eosin stain, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed. Furthermore, reverse transcription-PCR was carried out to evaluate mRNA levels of BAX, BAK1, CASP-3, and CASP-9. After CdCl2 challenge at both doses, a reduced cell viability and an overexpression of BAX, BAK1, CASP-3, and CASP-9 genes, as well as a high number of TUNEL-positive cells, were demonstrated, all parameters becoming higher as the dose of CdCl2 was increased. The pretreatment with Se-Met lowered the expression of all considered genes, improved cell viability and morphological changes, and reduced the number of TUNEL-positive cells. It was concluded that Se-Met plays a protective role against CdCl2-induced structural and functional changes in chondrocytes in vitro, as it improved cell viability and showed a positive role in the context of the apoptotic pathways. It is therefore suggested that a translational, multifaceted approach, with plant-based diets, bioactive functional foods, nutraceuticals, micronutrients, and drugs, is possibly advisable in situations of environmental pollution caused by potentially toxic elements.

Induction of Oxidative Stress and Ferroptosis in Triple-Negative Breast Cancer Cells by Niclosamide via Blockade of the Function and Expression of SLC38A5 and SLC7A11.

The amino acid transporters SLC38A5 and SLC7A11 are upregulated in triple-negative breast cancer (TNBC). SLC38A5 transports glutamine, methionine, glycine and serine, and therefore activates mTOR signaling and induces epigenetic modifications. SLC7A11 transports cystine and increases the cellular levels of glutathione, which protects against oxidative stress and lipid peroxidation via glutathione peroxidase, a seleno (Se)-enzyme. The primary source of Se is dietary Se-methionine (Se-Met). Since SLC38A5 transports methionine, we examined its role in Se-Met uptake in TNBC cells. We found that SLC38A5 interacts with methionine and Se-Met with comparable affinity. We also examined the influence of Se-Met on Nrf2 in TNBC cells. Se-Met activated Nrf2 and induced the expression of Nrf2-target genes, including SLC7A11. Our previous work discovered niclosamide, an antiparasitic drug, as a potent inhibitor of SLC38A5. Here, we found SLC7A11 to be inhibited by niclosamide with an IC50 value in the range of 0.1-0.2 µM. In addition to the direct inhibition of SLC38A5 and SLC7A11, the pretreatment of TNBC cells with niclosamide reduced the expression of both transporters. Niclosamide decreased the glutathione levels, inhibited proliferation, suppressed GPX4 expression, increased lipid peroxidation, and induced ferroptosis in TNBC cells. It also significantly reduced the growth of the TNBC cell line MB231 in mouse xenografts.

Complete labelling of pneumococcal DNA-binding proteins with seleno-L-methionine.

Streptococcus pneumoniae is a pathogenic and opportunistic Gram-positive bacterium that is the leading cause of community-acquired respiratory diseases, varying from mild- to deathly- infections. The appearance of antibiotic-resistant isolates has prompted the search for novel strategies and targets to tackle the bacterial resistances. One of the most promising approaches is the structure-based knowledge of possible targets in conjunction with rational design and docking of inhibitors of the chosen targets. A useful technique that helps to solve protein structures is to label them with an amino acid derivative like seleno-methionine that facilitates tracing of some of the amino acid residues. We have chosen two pneumococcal DNA-binding proteins, namely the relaxase domain of MobM protein from plasmid pMV158, and the RelB-RelE antitoxin-toxin protein complex. Through several changes that improve substantially a previous protocol (Budisa et al., 1995), we have used seleno-L-methionine to incorporate selenium into the amino acid sequence of the selected proteins. We have achieved 100% labelling of the proteins and could demonstrate that the labelled proteins retained full activity as judged from the relaxation of supercoiled plasmid DNA and from gel-retardation assays.

A practical method for efficient and optimal production of Seleno-methionine-labeled recombinant protein complexes in the insect cells.

The use of Seleno-methionine (SeMet) incorporated protein crystals for single or multi-wavelength anomalous diffraction (SAD or MAD) to facilitate phasing has become almost synonymous with modern X-ray crystallography. The anomalous signals from SeMets can be used for phasing as well as sequence markers for subsequent model building. The production of large quantities of SeMet incorporated recombinant proteins is relatively straightforward when expressed in Escherichia coli. In contrast, production of SeMet substituted recombinant proteins expressed in the insect cells is not as robust due to the toxicity of SeMet in eukaryotic systems. Previous protocols for SeMet-incorporation in the insect cells are laborious, and more suited for secreted proteins. In addition, these protocols have generally not addressed the SeMet toxicity issue, and typically result in low recovery of the labeled proteins. Here we report that SeMet toxicity can be circumvented by fully infecting insect cells with baculovirus. Quantitatively controlling infection levels using our Titer Estimation of Quality Control (TEQC) method allow for the incorporation of substantial amounts of SeMet, resulting in an efficient and optimal production of labeled recombinant protein complexes. With the method described here, we were able to consistently reach incorporation levels of about 75% and protein yield of 60-90% compared with native protein expression.

Comparative analysis of various sources of selenium on the growth performance and antioxidant status in broilers under heat stress / Análise comparativa de várias fontes de selênio no desempenho de crescimento e status antioxidante em frangos de corte sob estresse térmico

Abstract The supplementation of Selenium-enriched probiotics is effective in reducing oxidative stress and maintaining meat quality stability in broiler chicken especially under heat stress. An experimental study was conducted to perform Comparative analysis of Selenium yeast with inorganic Se in broilers under heat stress. A total of 120 broilers chicks of one day were assigned to 4 groups each consisting 30 chicks fed on same basal diet but different selenium sources. The basal diet of group D1 was not supplemented with Se source (Negative control), group D2 basal diet was supplemented with inorganic selenium (Sodium selenite 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase), group D3 basal diet was supplemented with commercially available organic selenium (Seleno-methionine 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase) and group D4 basal diet was supplemented with self-developed organic selenium (Se-enriched yeast 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase). The performance parameters i.e. feed intake (FI), live body weight (BW) and FCR were not significantly (p>0.05) effected by selenium supplementation in the starter phase but were significantly (p<0.05) effected in the finisher phase. Selenium supplementation significantly (p<0.05) effected serum Se level in different supplemented groups. Higher serum Se value (58.20±0.06) was recorded in D4 group. Similarly significantly lower selenium value was recorded for D4 and higher was recorded for D1 (11.36±0.08). However lower serum Paraoxonase (PON) value was recorded for D4 (13.24±0.01) and higher for D1 (13.33±0.03). Comparatively self-developed Se enriched yeast increased the Se accumulation and improved antioxidant system. Glutathione peroxidase (GPx) was found higher in D4 (12.333±0.03) followed by D3, D2 and D1 respectively. Whereas superoxide dismutase (SOD) was significantly lower (p<0.05) in D4 (0.1437±0.003) followed by D3 (0.1457±0.002). Selenium supplementation increased the bird's survival rate. Birds fed on Se enriched yeast showed higher Se deposition and better antioxidant capacity as compared to other sources of selenium. Se-enriched yeast displayed an improved result on Se deposition in tissues, and oxidative capacity, meat tenderness and immune response level as compared to other sources of selenium.

Resumo A suplementação de probióticos enriquecidos com selênio é eficaz na redução do estresse oxidativo e na manutenção da estabilidade da qualidade da carne em frangos de corte, especialmente sob estresse por calor. Um estudo experimental foi conduzido para realizar uma análise comparativa da levedura selênio com o Se inorgânico em frangos de corte sob estresse térmico. Um total de 120 pintos de um dia foi dividido em 4 grupos, cada um consistindo de 30 pintos alimentados com a mesma dieta basal, mas com diferentes fontes de selênio. A dieta basal do grupo D1 não foi suplementada com fonte de Se (controle negativo), a dieta basal do grupo D2 foi suplementada com selênio inorgânico (selenito de sódio 0,22 mg / kg fase inicial e 0,15 mg / kg fase finalizadora), a dieta basal do grupo D3 foi suplementada com selênio orgânico disponível comercialmente (fase inicial de seleno-metionina 0,22 mg / kg e fase finalizadora de 0,15 mg / kg) e a dieta basal do grupo D4 foi suplementada com selênio orgânico autodesenvolvido (fermento enriquecido com Se 0,22 mg / kg fase inicial e 0,15 mg / kg fase finalizadora). Os parâmetros de desempenho, ou seja, consumo de ração (FI), peso corporal vivo (PC) e FCR não foram significativamente (p > 0,05) afetados pela suplementação de selênio na fase inicial, mas foram significativamente (p < 0,05) afetados na fase final. A suplementação de selênio afetou significativamente (p < 0,05) o nível de Se sérico em diferentes grupos suplementados. O maior valor de Se sérico (58,20 ± 0,06) foi registrado no grupo D4. Da mesma forma, valor de selênio significativamente menor foi registrado para D4 e maior foi registrado para D1 (11,36 ± 0,08). No entanto, um valor mais baixo de Paraoxonase (PON) sérica foi registrado para D4 (13,24 ± 0,01) e mais alto para D1 (13,33 ± 0,03). A levedura enriquecida com Se comparativamente autodesenvolvida aumentou o acúmulo de Se e melhorou o sistema antioxidante. A glutationa peroxidase (GPx) foi encontrada maior em D4 (12,333 ± 0,03) seguido por D3, D2 e ​​D1 respectivamente. Enquanto a superóxido dismutase (SOD) foi significativamente menor (p < 0,05) em D4 (0,1437 ± 0,003) seguido por D3 (0,1457 ± 0,002). A suplementação de selênio aumentou a taxa de sobrevivência da ave. Aves alimentadas com levedura enriquecida com Se apresentaram maior deposição de Se e melhor capacidade antioxidante em comparação com outras fontes de selênio. A levedura enriquecida com Se apresentou um resultado melhorado na deposição de Se nos tecidos, capacidade oxidativa, maciez da carne e nível de resposta imune em comparação com outras fontes de selênio.

Comparative analysis of various sources of selenium on the growth performance and antioxidant status in broilers under heat stress / Análise comparativa de várias fontes de selênio no desempenho de crescimento e status antioxidante em frangos de corte sob estresse térmico

The supplementation of Selenium-enriched probiotics is effective in reducing oxidative stress and maintaining meat quality stability in broiler chicken especially under heat stress. An experimental study was conducted to perform Comparative analysis of Selenium yeast with inorganic Se in broilers under heat stress. A total of 120 broilers chicks of one day were assigned to 4 groups each consisting 30 chicks fed on same basal diet but different selenium sources. The basal diet of group D1 was not supplemented with Se source (Negative control), group D2 basal diet was supplemented with inorganic selenium (Sodium selenite 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase), group D3 basal diet was supplemented with commercially available organic selenium (Seleno-methionine 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase) and group D4 basal diet was supplemented with self-developed organic selenium (Se-enriched yeast 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase). The performance parameters i.e. feed intake (FI), live body weight (BW) and FCR were not significantly (p>0.05) effected by selenium supplementation in the starter phase but were significantly (p<0.05) effected in the finisher phase. Selenium supplementation significantly (p<0.05) effected serum Se level in different supplemented groups. Higher serum Se value (58.20±0.06) was recorded in D4 group. Similarly significantly lower selenium value was recorded for D4 and higher was recorded for D1 (11.36±0.08). However lower serum Paraoxonase (PON) value was recorded for D4 (13.24±0.01) and higher for D1 (13.33±0.03). Comparatively self-developed Se enriched yeast increased the Se accumulation and improved antioxidant system. Glutathione peroxidase (GPx) was found higher in D4 (12.333±0.03) followed by D3, D2 and D1 respectively. Whereas superoxide dismutase (SOD) was significantly lower (p<0.05) in D4 (0.1437±0.003) followed by D3 (0.1457±0.002). Selenium supplementation increased the [...].

A suplementação de probióticos enriquecidos com selênio é eficaz na redução do estresse oxidativo e na manutenção da estabilidade da qualidade da carne em frangos de corte, especialmente sob estresse por calor. Um estudo experimental foi conduzido para realizar uma análise comparativa da levedura selênio com o Se inorgânico em frangos de corte sob estresse térmico. Um total de 120 pintos de um dia foi dividido em 4 grupos, cada um consistindo de 30 pintos alimentados com a mesma dieta basal, mas com diferentes fontes de selênio. A dieta basal do grupo D1 não foi suplementada com fonte de Se (controle negativo), a dieta basal do grupo D2 foi suplementada com selênio inorgânico (selenito de sódio 0,22 mg / kg fase inicial e 0,15 mg / kg fase finalizadora), a dieta basal do grupo D3 foi suplementada com selênio orgânico disponível comercialmente (fase inicial de seleno-metionina 0,22 mg / kg e fase finalizadora de 0,15 mg / kg) e a dieta basal do grupo D4 foi suplementada com selênio orgânico autodesenvolvido (fermento enriquecido com Se 0,22 mg / kg fase inicial e 0,15 mg / kg fase finalizadora). Os parâmetros de desempenho, ou seja, consumo de ração (FI), peso corporal vivo (PC) e FCR não foram significativamente (p > 0,05) afetados pela suplementação de selênio na fase inicial, mas foram significativamente (p < 0,05) afetados na fase final. A suplementação de selênio afetou significativamente (p < 0,05) o nível de Se sérico em diferentes grupos suplementados. O maior valor de Se sérico (58,20 ± 0,06) foi registrado no grupo D4. Da mesma forma, valor de selênio significativamente menor foi registrado para D4 e maior foi registrado para D1 (11,36 ± 0,08). No entanto, um valor mais baixo de Paraoxonase (PON) sérica foi registrado para D4 (13,24 ± 0,01) e mais alto para D1 (13,33 ± 0,03). A levedura enriquecida com Se comparativamente autodesenvolvida aumentou o acúmulo de Se e melhorou o sistema [...].

Comparative analysis of various sources of selenium on the growth performance and antioxidant status in broilers under heat stress

Abstract The supplementation of Selenium-enriched probiotics is effective in reducing oxidative stress and maintaining meat quality stability in broiler chicken especially under heat stress. An experimental study was conducted to perform Comparative analysis of Selenium yeast with inorganic Se in broilers under heat stress. A total of 120 broilers chicks of one day were assigned to 4 groups each consisting 30 chicks fed on same basal diet but different selenium sources. The basal diet of group D1 was not supplemented with Se source (Negative control), group D2 basal diet was supplemented with inorganic selenium (Sodium selenite 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase), group D3 basal diet was supplemented with commercially available organic selenium (Seleno-methionine 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase) and group D4 basal diet was supplemented with self-developed organic selenium (Se-enriched yeast 0.22mg/Kg starter phase and 0.15mg/Kg finisher phase). The performance parameters i.e. feed intake (FI), live body weight (BW) and FCR were not significantly (p>0.05) effected by selenium supplementation in the starter phase but were significantly (p 0.05) effected in the finisher phase. Selenium supplementation significantly (p 0.05) effected serum Se level in different supplemented groups. Higher serum Se value (58.20±0.06) was recorded in D4 group. Similarly significantly lower selenium value was recorded for D4 and higher was recorded for D1 (11.36±0.08). However lower serum Paraoxonase (PON) value was recorded for D4 (13.24±0.01) and higher for D1 (13.33±0.03). Comparatively self-developed Se enriched yeast increased the Se accumulation and improved antioxidant system. Glutathione peroxidase (GPx) was found higher in D4 (12.333±0.03) followed by D3, D2 and D1 respectively. Whereas superoxide dismutase (SOD) was significantly lower (p 0.05) in D4 (0.1437±0.003) followed by D3 (0.1457±0.002). Selenium supplementation increased the birds survival rate. Birds fed on Se enriched yeast showed higher Se deposition and better antioxidant capacity as compared to other sources of selenium. Se-enriched yeast displayed an improved result on Se deposition in tissues, and oxidative capacity, meat tenderness and immune response level as compared to other sources of selenium.

Resumo A suplementação de probióticos enriquecidos com selênio é eficaz na redução do estresse oxidativo e na manutenção da estabilidade da qualidade da carne em frangos de corte, especialmente sob estresse por calor. Um estudo experimental foi conduzido para realizar uma análise comparativa da levedura selênio com o Se inorgânico em frangos de corte sob estresse térmico. Um total de 120 pintos de um dia foi dividido em 4 grupos, cada um consistindo de 30 pintos alimentados com a mesma dieta basal, mas com diferentes fontes de selênio. A dieta basal do grupo D1 não foi suplementada com fonte de Se (controle negativo), a dieta basal do grupo D2 foi suplementada com selênio inorgânico (selenito de sódio 0,22 mg / kg fase inicial e 0,15 mg / kg fase finalizadora), a dieta basal do grupo D3 foi suplementada com selênio orgânico disponível comercialmente (fase inicial de seleno-metionina 0,22 mg / kg e fase finalizadora de 0,15 mg / kg) e a dieta basal do grupo D4 foi suplementada com selênio orgânico autodesenvolvido (fermento enriquecido com Se 0,22 mg / kg fase inicial e 0,15 mg / kg fase finalizadora). Os parâmetros de desempenho, ou seja, consumo de ração (FI), peso corporal vivo (PC) e FCR não foram significativamente (p > 0,05) afetados pela suplementação de selênio na fase inicial, mas foram significativamente (p 0,05) afetados na fase final. A suplementação de selênio afetou significativamente (p 0,05) o nível de Se sérico em diferentes grupos suplementados. O maior valor de Se sérico (58,20 ± 0,06) foi registrado no grupo D4. Da mesma forma, valor de selênio significativamente menor foi registrado para D4 e maior foi registrado para D1 (11,36 ± 0,08). No entanto, um valor mais baixo de Paraoxonase (PON) sérica foi registrado para D4 (13,24 ± 0,01) e mais alto para D1 (13,33 ± 0,03). A levedura enriquecida com Se comparativamente autodesenvolvida aumentou o acúmulo de Se e melhorou o sistema antioxidante. A glutationa peroxidase (GPx) foi encontrada maior em D4 (12,333 ± 0,03) seguido por D3, D2 e D1 respectivamente. Enquanto a superóxido dismutase (SOD) foi significativamente menor (p 0,05) em D4 (0,1437 ± 0,003) seguido por D3 (0,1457 ± 0,002). A suplementação de selênio aumentou a taxa de sobrevivência da ave. Aves alimentadas com levedura enriquecida com Se apresentaram maior deposição de Se e melhor capacidade antioxidante em comparação com outras fontes de selênio. A levedura enriquecida com Se apresentou um resultado melhorado na deposição de Se nos tecidos, capacidade oxidativa, maciez da carne e nível de resposta imune em comparação com outras fontes de selênio.