RESEARCH ARTICLE Deletion of Genes Encoding Arginase Improves Use of “Heavy ” Isotope-Labeled Arginine for Mass Spectrometry in Fission Yeast

The use of “heavy ” isotope-labeled arginine for stable isotope labeling by amino acids in cell culture (SILAC) mass spectrometry in the fission yeast Schizosaccharomyces pombe is hin-dered by the fact that under normal conditions, arginine is extensively catabolized in vivo, resulting in the appearance of “heavy”-isotope label in several other amino acids, most nota-bly proline, but also glutamate, glutamine and lysine. This “arginine conversion problem” significantly impairs quantification of mass spectra. Previously, we developed a method to prevent arginine conversion in fission yeast SILAC, based on deletion of genes involved in arginine catabolism. Here we show that although this method is indeed successful when 13C6-arginine (Arg-6) is used for labeling, it is less successful whe