TY - JOUR A1 - Polatajko, A. A1 - Feldmann, I. A1 - Hayen, H. A1 - Jakubowski, Norbert T1 - Combined application of a laser ablation-ICP-MS assay for screening and ESI-FTICR-MS for identification of a Cd-binding protein in Spinacia oleracea L. after exposure to Cd N2 - We have studied the binding of the toxic element Cd to plant proteins and have used for this purpose spinach (Spinacia oleracea L.) plants treated with 50 µM Cd(II) as a model system. Laser ablation ICP-MS has been applied for the screening of Cd-binding proteins after separation by native anodal polyacrylamide gel electrophoresis (AN-PAGE) and electroblotting onto membranes. The main Cd-carrying protein band was isolated and investigated by nano-electrospray ionization–Fourier transform ion cyclotron resonance (FTICR) mass spectrometry after tryptic digestion. By this procedure, the main Cd-binding protein was identified as ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The latter enzyme has been discussed in the literature to be affected in its activity by oxidative stress induced by Cd. However, in this paper it is demonstrated for the first time that RuBisCO directly binds Cd and thus may be directly altered by this toxic element. A commercially available protein standard was used to verify direct binding of Cd(II) to the protein, even without metabolisation. The resulting metal–protein complex was shown to be stable enough to survive AN-PAGE separation and electroblotting. By the use of size exclusion chromatography coupled with ICP-MS it was demonstrated that the RuBisCO protein standard shows similar metal binding properties to Cd. Furthermore, essential elements such as Mn(II), Fe(II) and Cu(II), which are known to possibly replace the RuBisCO activator Mg(II), were investigated in addition to Zn(II). Again, similar binding properties in comparison to the plant protein were observed. PY - 2011 U6 - https://doi.org/10.1039/c1mt00051a SN - 1756-5901 SN - 1756-591X VL - 3 IS - 10 SP - 1001 EP - 1008 PB - RSC Publ. CY - Cambridge AN - OPUS4-24963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pedrero, Z. A1 - Murillo, S. A1 - Cámara, C. A1 - Schram, E. A1 - Luten, J.B. A1 - Feldmann, I. A1 - Jakubowski, Norbert A1 - Madrid, Y. T1 - Selenium speciation in different organs of African catfish (Clarias gariepinus) enriched through a selenium-enriched garlic based diet N2 - Speciation of Se in fish is needed to elucidate the metabolism of this element in living organisms in the marine environment. In this paper, selenium concentration and its species distribution in several organs and tissues (liver, gills, kidney, muscle and gastrointestinal tract) of African catfish fed with a selenium-enriched garlic based diet was studied. The intention of this paper is focused on both the investigation of selenium distribution in the soluble protein fraction and the detection of selenoaminoacids. Thus, two different procedures have been developed. In the first procedure, screening of selenium in proteins in the Tris-buffer soluble fraction of different tissues was carried out by size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) and by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) separation and electroblotting onto membranes. For the amino acid analysis, several sample treatments for Se-species extraction, based on enzymatic hydrolysis, were compared. The best results were obtained for incubation at controlled temperature. Application of several sample treatments in conjunction with different chromatographic techniques (reverse phase, anion exchange and ion exchange/size exclusion) was crucial to unambiguous Se-species identification. In Se-enriched African catfish a noticeable increase in the content of selenium in different organs was observed, except for the liver, where the Se level remained unaltered. The kidney was the Se-target organ in animals fed with enriched Se food. Selenomethionine (SeMet) was the main Se species identified in fillet extracts, whereas the presence of selenocysteine (SeCys) was detected in the liver and both SeMet and SeCys were present in the kidney. PY - 2011 U6 - https://doi.org/10.1039/c003889j SN - 0267-9477 SN - 1364-5544 VL - 26 IS - 1 SP - 116 EP - 125 PB - Royal Society of Chemistry CY - London AN - OPUS4-22981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -