An Interplay of Gases: Oxygen and Hydrogen in Biological Systems

Produced by photosynthesis, oxygen (O₂) is a fundamentally important gas in biological systems, playing roles as a terminal electron receptor in respiration and in host defence through the creation of reactive oxygen species (ROS). Hydrogen (H₂) plays a role in metabolism for some organisms, such as at thermal vents and in the gut environment, but has a role in controlling growth and development, and in disease states, both in plants and animals. It has been suggested as a medical therapy and for enhancing agriculture. However, the exact mode of action of H₂ in biological systems is not fully established. Furthermore, there is an interrelationship between O₂ and H₂ in organisms. These gases may influence each other’s presence in solution, and may both interact with the same cellular components, such as haem prosthetic groups. It has also been suggested that H₂ may affect the structures of some proteins, such as globins, with possible effects on O₂ movement in organisms. Lastly, therapies may be based on supplying O₂ and H₂ together, such as with oxyhydrogen. Therefore, the relationship regarding how biological systems perceive and respond to both O₂ and H₂, and the interrelationship seen are worth considering, and will be discussed here.