In this post, Ocean Insight examines how spectroscopy can characterize hemoglobin, myoglobin and cytochrome, which are key proteins in mammal physiology. The study of these proteins has implications for biomedical applications.
What Are Heme Proteins?
Heme groups bind to proteins and are critical for proteins to carry out their biological functions. Heme proteins have an iron atom at the center of a porphyrin prosthetic group, making them an extremely versatile example of a larger class of metalloproteins, a term used to describe any protein with a metal ion cofactor.
Hemoglobin and myoglobin are two common examples of metalloproteins. They are similar compounds that function to store and transport oxygen in mammalian cells. Another example of a metalloprotein is cytochrome c, which plays a critical role in the electron transport chain to aid in ATP synthesis.
Heme proteins play a vital role in mammal physiology. They store and transport oxygen in the bloodstream and transport electrons in the mitochondria to synthesize high-energy molecules used to drive cellular processes.
Heme Proteins and Spectroscopy
Heme groups generate absorbance bands, which vary based on the state of the heme group. Absorbance measurements can be used to study critical protein parameters, particularly protein conformation (structure), and to provide information on the binding and oxidation state of the heme prosthetic group.
The presence of the heme prosthetic group makes UV-Vis spectroscopy a powerful tool for studying heme proteins via their spectral changes. The prosthetic group gives rise to the absorbance spectra, which vary with the state of the heme group.
Heme proteins may carry up to four oxygen molecules, with the conformation of the protein being different depending on the presence of the oxygen molecule, and the number of bound oxygen molecules. As such, spectroscopy is a useful tool for measuring blood oxygen levels. This is important in a variety of medical applications, including situations where patients are sedated, comatose or otherwise unable to express nausea or faintness, which are common signs of low blood oxygenation.