See how many clues you need before you are convinced of being correct.
1. I am a large molecule detected in the vomeronasal (Jacobson’s) organ of snakes, giraffes and other animals. In mammals the sensory data from the base of the nasal cavity then travels directly to the brain’s amygdala, one of the centers of emotional learning.
2. Writing for the Smithsonian, Jennifer Margulius does not mention this molecule directly, but it’s what male giraffes detect in the urine of females if they subsequently engage in a slow neck-rubbing foreplay and prompt humping.
3. With an identical alpha subunit to that of the follicle stimulating hormone, it contains 92 amino acids in the human version but 96 in almost all other vertebrate species.
4. Since humans have a difficult time detecting this molecule with their own senses, they rely on another chemical which makes the presence of this molecule visible. Most women are only interested in this molecule when trying to conceive. On a graph, its concentration peaks like a sole stalagmite only at the time of ovulation.
The molecule is the glycoprotein leuteinizing hormone (LH), produced by the anterior pituitary gland. In case you are wondering, the gene that codes for this protein(which also plays a role in male testosterone production) is found on the sixth chromosome. More interestingly the chemistry of ovulation kits is described in detail at the http://www.madsci.org/posts/1268094346.Ch.q.html site by the biochemist Peter Hughes.