Not that kind of instrument“
Resonance” is right there in the name of nuclear magnetic resonance spectroscopy, but the technique doesn’t make most chemists think of music. Ayyalusamy Ramamoorthy, a biophysical chemist at the University of Michigan, thinks it should. Wanting a reliable way to teach NMR to students, he and graduate student Srikar Munukutla translated the NMR spectra of organic compounds into musical notes.
In traditional proton—or 1H—NMR, chemists use the chemical shifts of hydrogen atoms to help identify molecular structures. Normally reported in parts per million, these shifts are related to the electromagnetic frequencies that resonate with the nuclear spins of hydrogen atoms inside a big magnet. With a standard equation, chemists can convert the shifts into hertz—a measure of frequency in cycles per second. Music notes are also in hertz, so NMR spectra can be made into music.
The team took reported NMR spectra from more than 50 known compounds, such as benzene, alanine, and caffeine, converted the spectra’s peaks from parts per million to hertz, then turned these frequencies into musical notes. Munukutla fed these notes into the music app GarageBand. But this sounded like a mess, Ramamoorthy says. “The raw organic music as it comes from the molecule is not very pleasing or melodic,” he tells Newscripts, because the notes from the spectrum don’t fall in any particular order. So the team enlisted help from members of Michigan’s music school. “They used the notes to make it more melodious,” Ramamoorthy says.
The songs they created involved a lot of creative decisions, he says. First, they had to fudge a bit when matching peak frequencies to notes because the two didn’t line up perfectly. Musical notes played on a piano are discrete, and they have relatively large jumps between them relative to NMR peaks. So the researchers often couldn’t line up an NMR frequency exactly with a note. In addition, it’s common in NMR spectra to have split peaks—meaning that the signal can be two, three, or more peaks right next to each other. They treated these like single peaks because the frequency differences were too small to be separate notes, Ramamoorthy says.
“I’d been wanting to connect NMR with music to teach in an easy manner without knowing the math and physics,” Ramamoorthy says. NMR frequencies are “just like different tunes, different scales, which are easy to communicate.” You can hear some of their molecular tunes on YouTube (https://www.youtube.com/watch?v=p0oeO2xLe-I+), starting around the 9 min mark.
Ride of their lives
Fruit flies, Drosophila melanogaster, are ubiquitous in research to help scientists understand human diseases. But a group of scientists at the French National Center for Scientific Research is giving them something of a whirlwind treatment. In studying the neurodegenerative illness Huntington’s disease, the researchers are taking NMR spectra of live flies.
The group is looking at the metabolites of flies with disease-correlated genes. Some of the experiments look at the NMR spectra of crushed flies, but that’s not always accurate enough. “The metabolism of a living organism can change rapidly after death,” NMR specialist Vincent Sarou-Kanian tells Newscripts in an email. To see if the metabolites in live flies are the same as those in their crushed kin, the researchers use high-resolution magic-angle spinning NMR, generally used for mixed solid samples. They put a fly into a special insert to keep it centered in the instrument, then knock the fly unconscious by cooling it down to 4 °C. “Then we spin the rotor up to a frequency which allows getting a nice spectrum and keeping the physical integrity of the fly (e.g., before the abdomen breaks!),” Sarou-Kanian says. After 30 min at 2,630 Hz, the flies can fly normally again.
The researchers usually euthanize the flies afterward, as it’s hard to get them out of the insert without damaging them, he says. “But once we stored some flies back in their tube (with food). And they lived for a long time,” Sarou-Kanian says. He says he doesn’t know what such an “extreme experience” does to the flies’ life expectancy, but the team is also very curious about this. Preliminary data suggest that the spectra of the flies, both crushed and whole, are very similar.
Please send comments and suggestions to email@example.com.
This story was updated on Dec. 1, 2021, to correct what nuclear magnetic resonance spectroscopy measures. NMR measures atoms’ nuclear spin, not electrons’ spin.