- Paula Aracena asked a question:What makes the difference between selenocysteine and cysteine residues in terms of enzymatic catalysis?This is almost a philosophical question, but I have always been mesmerized by the fact that a selenocysteine residue is a key residue for glutathione peroxidase catalysis. Are there studies comparing activities of Se-cysteine-containing and Cys-containing glutathione peroxidase? I am fairly ignorant in this matter, but I had to ask!Following
- Claudio Davet Gutiérrez Lazos added an answer:What conditions are best to reduce selenium powder by sulfurous acid? Should I dissolve the sulfurous acid in water or heat it until it melts?I am trying to synthesize CdSe quantum dots in aqueous solution and right now I am using hydrazine hydrate as reducing agent for selenium powder, but I want to try metol or sulfurous acid instead.Following
- Jochen Vogl added an answer:How can I remove possible sulfur interference in HG-ICP-MS total selenium analysis of biological tissue?We have 90-92% recovery for total Se when analyzing biological CRM (fish or clam tissue). Recovery is ~100% for sediment CRM. We have tried different extraction methods and isotope dilution but always get the same result.mass spectrometric interfences ususally lead to an increased signal intensity and not to a decreased one. When you get the same result for different Se isotopes it is a hint that there is no problem with interferences. Also in hydride generation you have less interferences than in normal ICPMS. potentail sources of errors could be incomplete extraction/digestion or strong matrix effects. I would try to completely digest the samples e.g. by a microwave assisted acid digestion. Another potential sourec is that you do have different yield in the hydride generation process for biological samples. A complete digestion could help here also.Following
- Nagarajan Srinivasan asked a question:Role of selenium with herbal drugs in cancer therapy?Is it effective?Following
- Behnam Beigzadeh added an answer:role of polysacharide in selenium nanoparticle systhesiscan anyone pls explain the role of polysacharide during systhesis of selenium nanoparticle. i need to specifically know if its use to stabllise the nanoparticles or does it contribute to the size reduction of the nanoparticles.Following
- Majid Darroudi added an answer:Can anyone suggest how to reduce the size of biologically synthesized selenium nanoparticles?Currently I am getting nanoparticle size of 150-250 nm. I would like to reduce this size to less than 100 nm.You can use of physical methods after Se fabrication for reducing the size such as UV-irradiation or pulsed laser (As N. Barsch's suggestion), ...Following
- Bram Bekaert added an answer:Which form of selenoprotein exists in Se-enriched yeast?We know that no selenoprotein synthesis system has been discovered in yeast and higher plants. How do the Se-yeast produce selenoproteins? Are they only the selenium-containing proteins (I mean the selenium is in protein not in selenocysteine or SeMet), or do the proteins contain Secys residues? If the yeast lack the Sec(Secys) incorporation machinery, does that mean that the selenoprotein gene from mammals can't be expressed in Se-enriched yeast?Selenium in selenium-enriched yeast produced using sodium selenite as a source is typically in the form of the seleno-amino acid selenomethionine, accounting for approximately 60-85% of total selenium species in the selenium-enriched yeast product. Selenocysteine is the second most abundant identified species, approximating to 2-4% of total selenium species. Inorganic selenium (IV) ion is normally found at less than 1% of total, confirming that virtually all of the selenium present in the product is organically bound. The remaining proportion is the sum of minor species. Reference: The EFSA Journal (2008) 766, 1-42 BramFollowing
An element with the atomic symbol Se, atomic number 34, and atomic weight 78.96. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of GLUTATHIONE PEROXIDASE.