Detection of selenoproteins in human cell extracts by laser ablation-ICP MS after separation by polyacrylamide gel electrophoresis and blotting
Résumé
Laser ablation-ICP MS was optimized for the sensitive detection of selenoproteins in polyacrylamide gel and PVDF membrane after blotting. For this purpose, two interlaboratory reference samples were prepared: glutathione peroxidase band in the gel and on the membrane, respectively. The optimisation was carried out using two systems: 213 nm laser (Newwave) - Agilent 7500ce ICP MS, and a 1030 nm high repetition rate femtosecond laser with galvanometric optics (Novalase) - PE/SCIEX DRCII. Sensitivity and signal-to-noise ratio were benchmarked to those obtained for the same sample by a recently published method in a reference lab. The optimization allowed a 12-fold gain of the S/N ratio during ablation of gels and a 3.5-fold gain in the ablation of blots in comparison with the method using an essentially similar system published by the reference lab. The gain of S/N by increasing ablation surface using the high repetition rate laser was not as spectacular as expected (2.5-fold for the gels and 1.5-fold for the blots) as the background noise increased considerably when a larger surface is ablated due to selenoproteins peak tailing. The study allowed for the first time LA-ICP MS detection of selenoproteins (separated by gel electrophoresis) in human cell extracts with the selenium concentration at the 10 ng ml -1 level.