Miniscule genetic differences in amino acids can determine whether you enjoy or are repulsed by a scent; this explains why some people love the smell of patchouli while others hate it.
There are around 400 genes coding for the receptors in the human nose, and 900,000 gene variations, a Duke University news release reported.
The receptors work a little differently for everybody, the researchers determined there is roughly a 30 percent difference between any two people.
"There are many cases when you say you like the way something smells and other people don't. That's very common," study leader Hiroaki Matsunami said. "We found that individuals can be very different at the receptor levels, meaning that when we smell something, the receptors that are activated can be very different (from one person to the next) depending on your genome."
Researchers had already pinpointed the genes that encode for odor processing in the past, but up until now they weren't sure how those genes were activated.
The team cloned about 500 receptors to determine what turned them on. The receptors were taken from 20 people that had slight differences in amino acids. They then exposed the receptors to different scent molecules to see how they reacted.
The receptors were exposed to one, 10, or 100 micromoles of 73 various odorants. Through this method the team was able to identify 27 receptors that responded to certain odorants.
The study doubled the number of "odorant-activated receptors" that researchers know of, raising it to 40.
The findings could provide useful information to the food and fragrance industries.
These manufacturers all want to know a rational way to produce new chemicals of interest, whether it's a new perfume or new-flavored ingredient, and right now there's no scientific basis for doing that," Matsunami said. "To do that, we need to know which receptors are being activated by certain chemicals and the consequences of those activations in terms of how we feel and smell."
