Identification of alpha2u-globulin and bound volatiles in the Indian common house rat (Rattus rattus)

The alpha2u-globulin (alpha2u) is a pheromone carrier urinary protein believed to be relevant for sexual communication among rats and is characterized in laboratory rats. In the present study 17 kDa protein and the bound pheromones were characterized in a population of wild-type Indian common house rat (Rattus rattus). The protein was purified by two runs of Sephadex G-50 chromatography and analyzed with SDS-PAGE with MALDI-TOF/MS. The results of MASCOT search identified the protein as an alpha2u and suggested a role for binding pheromones. To confirm the protein bound volatiles, purified alpha2u was extracted with dichloromethane and volatile molecules were detected using of gas chromatography linked to mass spectrometry (GC-MS). 1-Chlorodecane was detected as the predominant compound and 2-methyl-N-phenyl-2-propenamide, hexadecane and 2,6,11-trimethyl decane as the minor compounds. The simple method of protein purification and the identification of bound volatiles may help in designing efficient pheromone-based rat traps.