“Bile salts are organic molecules with a structure that shows an unsettled instability, a wobble, an anthropomorphic élan more characteristic of life and of growing organisms. Among the types of molecules that make up life from its simplest forms to the most complex, bile salts are sparkling little bits of creativity standing out amidst a sea of mainstream soldier-like molecules that tramp, tramp, tramp, march in lockstep formation.”
-Lee R. Hagey, Ph.D.
What are Bile Acids?
Bile acids are a family of cholesterol derived steroidal acids synthesized in the liver and are well known for their important role in facilitating fat and oil digestion as well as cholesterol catabolism. When conjugated with amino acids for the formation of bile salts, these molecules are continuously undergoing changes induced by both internal and external environmental factors.
Bile acids, bile salts, and their derivatives can be found playing contributing roles in a vast variety of living organisms from mammals to reptiles, amphibians, birds, and more. Overtime, these molecules have been silently evolving with their hosts. Peculiar cases can be found within the relationships between these molecular structures and their surrounding gut microbiomes. The results of this relationship manifested themselves into mysterious and unique structural modifications. While some forms dominate, there is a vast spectrum of unknown players waiting to be discovered, and hopefully give more insight into their functions and the world of bile acids.
What is mass spectrometry?
The primary way we analyze our samples is through a technique called Mass spectrometry (MS). A mass spectrometer measures the mass-to-charge ratio (m/z) of various molecules that can give insight into their isotopic signatures, molecule mass, purity, chemical structure, and various chemical properties. The mass spectrometer performs three critical steps:
- First the sample goes through ionization where its molecules are converted to ions that can be manipulated by magnetic and electric fields. After ionization, the molecules become positively or negatively charged ions that can proceed to the next step.
- The next step prepares the ions by separating them via mass and charge (m/z).
- Lastly, the separated ions are organized where the data is displayed in a mass spectrum which plots the m/z ratios against their intensities/relative abundance.
We can compare these results to the masses of known molecules or by their unique fragmentation patterns! Through careful analysis of these mass spectrum plots we can slowly decipher and begin to understand different features of bile acids at a molecular level.