Efficiency Study and Evaluation of Enzyme Hydrolysis Procedures for Selenium Enriched Yeast Using Inductively Coupled Plasma - Mass Spectrometric Detection

摘要

Various combinations of the enzymes Proteinase K, Aminopeptidase M, and Carboxypeptidase Y were studied as treatment procedures to extract and hydrolyze selenoamino acids from commercially produced selenium enriched yeast. Elemental speciation analysis and total selenium levels were measured in the extract solutions. A C8 high performance liquid chromatographic (HPLC) column was used for the chromatographic determination of selenomethionine using a mobile phase of 89/10/1 (v/v/v) water/methanol/trifluoroacetic acid. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for the total selenium content and ICP-MS was used as the detector coupled with HPLC for the selenomethionine determinations. Two of the combination procedures were the treatment of selenium yeast with Proteinase K and Aminopeptidase M simultaneously and a sequential treatment using Proteinase K first followed with Carboxypeptidase Y. Both of these combination enzyme treatments gave selenomethionine as the major product as high levels, 68 and 64 percent selenium recovered, respectively, of the total selenium level in the yeast determined by nitric acid digestion. These two treatment procedures also produced chromatograms containing few peaks suspected of being the result of incomplete enzymatic hydrolysis.