Mapping of selenium metabolic pathway in yeast by liquid chromatography-Orbitrap mass spectrometry.
A high-resolution mass spectrometric detection method is described for the identification of key metabolites in the selenium pathway in selenium enriched yeast. Iodoacetic acid (IAA) was used as the derivatizing reagent to stabilize the selenols. Oxidized forms of selenocysteine (Se-Cys), selenohomocystine (Se-HCys), selenoglutathione (Se-GSH), seleno-γ-glutamyl-cysteine (Se-Glu-Cys), N-(2,3-dihydroxy-1-oxopropyl)-selenocysteine (Se-DOP-Cys), N-(2,3-dihydroxy-1-oxopropyl)-selenohomocysteine (Se-DOP-HCys), selenomethionine (SeMet), seleno-S-adenosyl-homocysteine (Se-AdoHcy), the conjugate of glutathione and N-(2,3-dihydroxy-1-oxopropyl)-selenocysteine (GSH-Se-DOP-Cys), and the conjugate of glutathione and N-(2,3-dihydroxy-1-oxopropyl)-selenohomocysteine (GSH-Se-DOP-HCys) were found in the selenium enriched yeast certified reference material (SELM-1). Selenols were also derivatized with a mercury tag, p-hydroxymercurybenzoate (PHMB). The selenol-PHMB complexes showed the overlapped isotopic patterns of selenium and mercury, which provided supporting information for the identification of selenols. Both methods showed good agreement (<4 ppm difference) between the theoretical masses of the target compounds and the measured masses in the yeast matrix. The method using IAA as the derivatizing reagent was used to study the response of Saccharomyces cerevisiae to three forms of selenium, Se-Met, Na(2)SeO(3) (Se(IV)), and Na(2)SeO(4)·10H(2)O (Se(VI)) (concentration of Se: 100 mg/L). The production of selenocompounds observed over a 6 h period was high in the Se-Met treated group compared to the groups treated with Se(IV) and Se(VI).
Rao
Yulan
Y
Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada.
McCooeye
Margaret
M
Windust
Anthony
A
Bramanti
Emilia
E
D'Ulivo
Alessandro
A
Mester
Zoltán
Z
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006711:Homocystine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D019807:Iodoacetic Acid / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008628:Mercury / Q000737:chemistry; D053858:Metabolic Networks and Pathways; D016566:Organoselenium Compounds / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012643:Selenium / Q000737:chemistry / Q000378:metabolism*; D018036:Selenium Compounds / Q000737:chemistry / Q000378:metabolism; D017279:Selenocysteine / Q000737:chemistry / Q000378:metabolism; D012645:Selenomethionine / Q000737:chemistry / Q000378:metabolism
D016566:Organoselenium Compounds; D018036:Selenium Compounds; C455269:selenohomocystine; C442270:selenol; D017279:Selenocysteine; D006711:Homocystine; D012645:Selenomethionine; D008628:Mercury; D012643:Selenium; D019807:Iodoacetic Acid