Stephen Russell

The effect of selenium enrichment on baker's yeast proteome.

The use of regular yeast (RY) and selenium-enriched yeast (SEY) as dietary supplement is of interest because the Nutritional Prevention of Cancer (NPC) trial revealed that SEY but not RY decreased the incidence of prostate cancer (PC). Using two-dimensional difference in gel electrophoresis (2D-DIGE)-tandem mass spectrometry (MS/MS) approach, we performed proteomic analysis of RY and SEY to identify proteins that are differentially expressed as a result of selenium enrichment. 2D-DIGE revealed 96 candidate protein spots that were differentially expressed (p≤0.05) between SEY and RY. The 96 spots were selected, sequenced by LC/MS/MS and 37 proteins were unequivocally identified. The 37 identified proteins were verified with ProteinProphet software and mapped to existing Gene Ontology categories. Furthermore, the expression profile of 5 of the proteins with validated or putative roles in the carcinogenesis process, and for which antibodies against human forms of the proteins are available commercially was verified by western analysis. This study provides evidence for the first time that SEY contains higher levels of Pyruvate Kinase, HSP70, and Elongation factor 2 and lower levels of Eukaryotic Translation Initiation Factor 5A-2 and Triosephosphate Isomerase than those found in RY.

Selenium-responsive proteins in the sera of selenium-enriched yeast-supplemented healthy African American and Caucasian men.

Background: Studies have shown that supplementation of adult men with selenium-enriched yeast (SY) was protective against prostate cancer (PCa) and also reduced oxidative stress and levels of prostate-specific antigen. Here, we determined the effect of SY supplementation on global serum protein expression in healthy men to provide new insights into the mechanism of selenium chemoprevention; such proteins may also serve as biomarkers of disease progression. Methods: Serum samples from 36 adult men were obtained from our previous SY clinical trial, 9 months after supplementation with either SY (247 μg/d; n = 17) or placebo (nonenriched yeast; n = 19). Results: Proteomic profiling using two-dimensional difference in gel electrophoresis followed by liquid chromatography-tandem mass spectrometry revealed a total of 1,496 candidate proteins, of which, 11 were differentially expressed in the SY group as compared with placebo. Eight proteins were upregulated [clusterin isoform 1 (CLU), transthyretin, α-1B-glycoprotein, transferrin, complement component 4B proprotein, isocitrate dehydrogenase, haptoglobin, and keratin 1] and three proteins were downregulated [α-1 antitrypsin (AAT), angiotensin precursor, and albumin precursor] by SY. All of the identified proteins were redox-sensitive or involved in the regulation of redox status. Because both AAT and CLU have been previously linked to PCa development, their identities were confirmed by two-dimensional Western blot analysis. Conclusions: We identified AAT and CLU as potential candidate proteins involved in the mechanism of PCa prevention by SY. Collectively, proteins identified in this study might serve as potential new biomarkers for monitoring and comparing responses to selenium-based chemopreventive agents. Impact: Proteomic analysis of serum might be useful for the early detection and monitoring efficacy of chemopreventive agents. Cancer Epidemiol Biomarkers Prev; 19(9); 2332–40. ©2010 AACR.

ProDM™ – A kit for tryptic digestion monitoring for a successful shotgun proteomics

©2012 ITSI-Biosciences, LLC |AUGUST 2012| 1 ProDMTM – A kit for tryptic digestion monitoring for a successful shotgun proteomics Successful shotgun proteomics depends on optimal digestion of proteins into peptides prior to LC/MS/MS. Current methods to determine the status of protein digestion are time consuming and/or require expensive reagents and equipment. We describe a method for determining the extent of protein digestion using ProDMTM kit and a basic spectrophotometer. Determining whether the protein is digested or not prior to LC/MS/MS will avoid wasting instrument time, samples and money.