ABSTRACT
The 2u-globulin (2u) 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 2u and suggested a role for binding pheromones. To confirm the protein bound volatiles, purified 2u 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.
Subject(s)
Acrylamides/analysis , Alkanes/analysis , Alpha-Globulins/chemistry , Alpha-Globulins/metabolism , Animals , Chromatography, Gel , Electrophoresis, Polyacrylamide Gel , Gas Chromatography-Mass Spectrometry/methods , Hydrocarbons, Chlorinated/analysis , Male , Mass Spectrometry/methods , Methylene Chloride/analysis , Pest Control , Pheromones/chemistry , Pheromones/metabolism , Proteins/metabolism , RatsABSTRACT
The low molecular mass proteins found in the pheromonal sources such as urine, saliva, glandular secretion etc have been reported as ligand carriers for the processes of chemocommunication in mammals. The preputial gland plays an important role in the production of olfactory signals for pheromonal communication. Thus, in the present study, alpha-2u globulin having molecular mass of 18 kDa has been identified in the preputial gland of Norway rat (Rattus norvegicus) by in-gel trypsin digestion and analyzing the resulting peptides by MALDI-TOF. Since preputial gland is one of the major pheromonal sources in rat, the results suggest that alpha-2u globulin might act as a carrier for hydrophobic odorants of preputial gland.
Subject(s)
Alpha-Globulins/chemistry , Amino Acid Sequence , Animals , Carrier Proteins/chemistry , Genitalia, Male/metabolism , Lipocalin 1 , Male , Molecular Sequence Data , Peptides/chemistry , Pheromones/chemistry , Protein Binding , Rats , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Trypsin/chemistryABSTRACT
Alpha-globulin, the high molecular weight protein fraction from sesame (Sesamum indicum L.) seed, was hydrolysed by alpha-chymotrypsin. The hydrolysate was resolved into two fractions, the hydrolysed part and the unhydrolysed part of alpha-globulin using gel filtration on Sepharose 6B-100. The unhydrolysed alpha-globulin residue was characterized for its sedimentation coefficient, subunit composition, fluorescence emission spectrum, secondary structure, and other biophysical properties. The results indicated a decrease in the size of the protein molecule upon hydrolysis to a very small extent. The effect of hydrolysis products on hydrolysis of native alpha-globulin as well as on a standard substrate, casein, was also investigated. The results indicated that the hydrolysis products contribute to the resistance of alpha-globulin to proteolysis by alpha-chymotrypsin to the extent of 40%.