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).

Dried-droplet laser ablation ICP-MS of HPLC fractions for the determination of selenomethionine in yeast

“…The extraction procedure used in this study followed that described previously 23,24 and is similar to that reported by Wrobel, et al 25 Three sample blanks and four 0.20 g subsamples of yeast were prepared at the same time. Samples were diluted 5-fold prior to HPLC-ICP-MS analysis.…”

Speciation, quantification and stability of selenomethionine, S-(methylseleno)cysteine and selenomethionine Se-oxide in yeast-based nutritional supplements

“…24 Higher extraction efficiencies have been achieved with proteolytic enzymes, 25 hydrochloric acid 26 and methanesulfonic acid. 27 The more widely employed proteolytic enzymes for species liberation, most closely resemble the physiological conditions in the human intestine, whereas harsher chemical hydrolysis may cause degradation or alteration of selenium species of physiological importance. Enzymatic hydrolysis usually requires long extraction periods but a rapid extraction procedure using focused ultrasound in conjunction with enzymatic hydrolysis, enzymatic probe sonication (EPS), for total selenium and selenomethionine determination in selenium-enriched yeast has been reported.…”

The effect of dietary Se supplementation on the Se status and physico-chemical properties of eggs - a review

“…Skřivan (2009) and Heindl et al (2010) claimed that selenomethionine represents 54-74% of the total selenium contained in selenium yeast. Wrobel et al (2003) reported that the selenomethionine in yeast comprised 65% of total selenium. However, according to the data of Schrauzer (1998), in yeast more than 90% of the total Se content consists of l-selenomethionine, with only traces of inorganic Se.…”