Secreted Protein Acidic and Rich in Cysteine (SPARC) Protein SRM/MRM Assay

摘要

The current disclosure provides for specific peptides, and derived ionization characteristics of the peptides, from the Secreted Protein Acidic and Rich in Cysteine (SPARC) protein that are particularly advantageous for quantifying the SPARC protein directly in biological samples that have been fixed in formalin by the method of Selected Reaction Monitoring (SRM) mass spectrometry, or what can also be termed as Multiple Reaction Monitoring (MRM) mass spectrometry. Such biological samples are chemically preserved and fixed wherein said biological sample is selected from tissues and cells treated with formaldehyde containing agents/fixatives including formalin-fixed tissue/cells, formalin-fixed/paraffin embedded (FFPE) tissue/cells, FFPE tissue blocks and cells from those blocks, and tissue culture cells that have been formalin fixed and or paraffin embedded. A protein sample is prepared from said biological sample using the Liquid Tissue™ reagents and protocol and the SPARC protein is quantitated in the Liquid Tissue™ sample by the method of SRM/MRM mass spectrometry by quantitating in the protein sample at least one or more of the peptides described. These peptides can be quantitated if they reside in a modified or an unmodified form. An example of a modified form of an SPARC peptide is phosphorylation of a tyrosine, threonine, serine, and/or other amino acid residues within the peptide sequence.