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eFOOD-Lab_International_02_2014

peptides peptides peptides peptides Peptide identification with HRMS Selection of suitable peptides MRM method development final MRM method Figure 2: Workflow: Method development for the species identification of specific peptides using MRM detection. teomics as it nowadays allows the highly parallel analysis of hundreds or even thousands of proteins. Targeted proteomics addresses the analysis of a limited number of proteins of interest for example by the detection of proteotypic marker peptides that are generated enzymatically from the proteins. This approach is especially useful when proteins have to be quantified or detected with high accuracy. The proteome of mammalian cells is highly complex with estimated 20,000 different proteins per cell that in addition can occur in different proteoforms and which show incredible differences in copy numbers 2. Similar to the genome, the proteome of even closely related species have enough sequence differences to reliably distinguish between species. Using targeted proteomics, the sensitive and specific detection of proteins and peptides is now at hand. Method development One of the major tasks during method development is the identification of species-specific biomarker proteins that, under ideal conditions, are highly abundant in the given tissue. In general, sequence identity on protein level is about 90-95%, resulting in far less than 1% of sequence polymorphisms that can be used for the development of a mass spectrometrical method. (Fig. 1). First attempts for the identification of sequence differences between species have mainly been performed using gel electrophoretical techniques such as 2D-PAGE which separates proteins by size and isoelectric point. Differences in the resulting protein pattern can then be used for species identification but one of the major drawbacks is the limited reproducibility caused by gel to gel variability. 5500 Peptide •Identifikation der Peptide mittels HRMS 500 Peptide •Auswahl analytisch geeigneter Peptide 70 Peptide •MRM-Methodenentwicklung 10 Peptide •finale MRM-Methode Figure 3: Increased specificity and sensitivity for the detection of peptide marker using MRM3. State of the Art Technology Elmasonic S 50 R Elmasonic S 350 R New: for sieves of 200 & 500 mm diameter • test sieve cleaning with program-controlled ultrasound • special program for sample preparation • efficient and quick degassing of samples and HPLC solvents Elma Hans Schmidbauer GmbH & Co. KG Gottlieb-Daimler-Str. 17 · D-78224 Singen info@elma-ultrasonic.com www.elma-ultrasonic.com


eFOOD-Lab_International_02_2014
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