The primary structure of aphrodisin.

No prior work had resolved the complete amino acid sequence of the hamster vaginal protein known as aphrodisin. This molecule serves as a chemical signal that stimulates mating responses in males through the accessory olfactory system. Researchers previously identified its presence in vaginal discharge but lacked detailed structural data. That uncertainty drove the need for a comprehensive analysis of its primary composition. Prior research has shown that similar proteins exist in other rodents, yet the specific hamster variant remained uncharacterized. Understanding this protein is necessary to clarify how chemical cues influence mammalian reproductive behavior. This gap motivated the current investigation into its precise molecular architecture. Scientists sought to define the sequence and post-translational modifications of this signaling agent.

The study aimed to determine the complete primary structure of the hamster vaginal protein known as aphrodisin. Researchers sought to resolve the sequence of this signaling molecule to understand its biological function. The team investigated how this protein interacts with the accessory olfactory system to influence mating. They addressed the lack of structural information regarding its amino acid composition and post-translational modifications. This work was motivated by the need to compare the hamster protein with known rodent signaling molecules. The investigators intended to map the disulfide bridges and sugar attachment sites within the protein chain. By defining these features, the authors hoped to clarify its classification among extracellular proteins. This effort provides a detailed molecular profile to support future behavioral research in hamsters.

The team determined the primary sequence by analyzing intact protein samples after removing terminal blocks. They employed pyroglutamate aminopeptidase to expose the amino terminus for subsequent identification. Enzymatic digestion using trypsin and Lys-C generated smaller peptide fragments for detailed examination. The investigators then utilized cyanogen bromide and hydroxylamine to facilitate the alignment of these fragments. This strategy provided the necessary overlap to reconstruct the full sequence of 151 residues. The researchers verified the positions of specific cysteine residues involved in disulfide bonding. They also identified the sites of sugar attachment by analyzing the modified asparagine residues. This rigorous analytical approach ensured the accurate characterization of the protein composition.

The protein consists of exactly 151 amino acid residues with a molecular weight of 17,000. The analysis revealed disulfide bonds linking cysteine residues at positions 38 and 42. A second set of disulfide bonds connects residues at positions 57 and 149. The researchers identified N-acetylglucosamine residues attached to asparagines at positions 41 and 69. Sequence alignment confirmed the protein shares significant similarities with major urinary proteins in rats. These findings support the categorization of the molecule within the alpha 2u-globulin superfamily. The study successfully mapped the entire primary structure after unblocking the amino terminus. This comprehensive data set provides the first complete description of the hamster vaginal signaling protein.

The authors propose that aphrodisin functions as a key member of the alpha 2u-globulin superfamily. This classification relies on observed similarities between the hamster protein and major urinary proteins found in other rodents. The researchers identified two specific asparagine sites where sugar molecules attach to the protein chain. Two distinct disulfide bridges provide structural stability by connecting cysteine residues at specific locations. The study confirms the protein contains 151 amino acids with a molecular weight of approximately 17,000. These structural details clarify how the protein might interact with the vomeronasal organ. The team suggests that this protein architecture supports its role in eliciting copulatory behavior. This work provides a foundation for future studies on how extracellular proteins mediate pheromonal signaling.