In vitro induction and proteomics characterisation of a uranyl–protein interaction network in bovine serum†
Uranyl ions (UO22+) were shown to interact with a number of foetal serum proteins, leading to the formation of a complex that could be isolated by ultracentrifugation. The molecular weight of the complex was estimated based on size-exclusion chromatography as 650 000 Da. Online ICP AES detection indicated that UO22+ in the complex co-eluted with minor amounts of calcium and phosphorous, but not with magnesium. A 1D gel electrophoresis of the U-complex produced more than 10 bands of similar intensity compared with only 2–3 intense bands corresponding to the main serum proteins in the control serum, indicative of the specific interaction of UO22+ with minor proteins. A proteomics approach allowed for the identification of 74 proteins in the complex. Analysis of the protein–protein interaction network in the UO22+ complex identified 32 proteins responsible for protein–protein complex formation and 34 with demonstrated ion-binding function, suggesting that UO22+ stimulates the formation of protein functional networks rather than using a particular molecule as its target.