Proteomic analysis of the effect of storage temperature on human serum

This study examined the effect of storage temperature on the protein profile of human serum. Serum samples were stored for > or =7 days at -80 degrees C, -20 degrees C, 4 degrees C, and room temperature prior to proteomic analysis. Serum protein fractionations by SDS-PAGE, including high and low molecular weight (MW) proteins, showed that several bands had different intensities after storage at higher temperatures. Fractionations by 2-dimensional gel electrophoresis (2-DE) indicated that approximately 60 protein spots had changed significantly after storage at higher temperatures. These proteins included C3/C4, alpha2-macroglobulin, and alpha1B glycoprotein, based on identification by MS and MS/MS. The profile of the low MW serum proteins, analyzed using SELDI ProteinChip Arrays (IMAC3 and Q10), was also significantly changed after storage at higher temperatures. These results indicate that the higher storage temperatures have a significant influence on serum protein profiles regardless of MW. Based on these findings, serum specimens should be preferably be stored at -80 degrees C before proteomic analysis.