title: Hydrolysis of proteins with methanesulfonic acid for improved HPLC-ICP-MS determination of seleno-methionine in yeast and nuts.
abstract: In this work, the use of methanesulfonic acid for protein hydrolysis is proposed for evaluation of Se-methionine in yeast, Brazil nuts, and possibly other selenium-rich biological samples. The hydrolysis was carried out by heating the sample with 4 mol L(-1) acid at reflux for 8 h. Two chromatographic techniques (size-exclusion and ion-pairing) coupled with ICP-MS detection were used to compare the release of Se-methionine from proteins by enzymatic (proteinase K, protease XIV) and acid hydrolyses. A more efficient liberation of Se-methionine was observed by acid hydrolysis. For quantification, the sample extracts were introduced onto a C8 Alltima column, and the separation was achieved with a mobile phase containing 5 mmol L(-1) hexanesulfonic acid in citrate buffer (pH 4.5)/methanol (95:5). The results obtained by standard addition showed 816+/-17 micro g g(-1) and 36.2+/-1.5 micro g g(-1) of selenium in the form of Se-methionine in yeast and nuts, respectively (65% and 75% of total selenium).
authors.affiliation: Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221-0172, USA.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Wrobel
authors.forename: Sasi S
authors.initials: SS
authors.lastname: Kannamkumarath
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Wrobel
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Caruso
mesh_terms: D002851:Chromatography, High Pressure Liquid; D019286:Endopeptidase K / Q000737:chemistry; D006868:Hydrolysis; D013058:Mass Spectrometry; D008698:Mesylates / Q000737:chemistry*; D009754:Nuts / Q000737:chemistry*; D011402:Pronase / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012645:Selenomethionine / Q000032:analysis*; D015002:Yeast, Dried / Q000737:chemistry*
chemical_list: D008698:Mesylates; D011506:Proteins; C045880:methanesulfonic acid; D012645:Selenomethionine; D019286:Endopeptidase K; D011402:Pronase