Archive | September 2016

The evolutionary importance of iron sulphur flavoproteins

Iron Sulphur Flavoproteins.

This posting explores how evolution may have brought together flavoproteins and iron-sulphur clusters (as co-factors) to optimise a range of functions – including in sequence. Iron-sulfur clusters rank with biological prosthetic groups, such as hemes and flavins in pervasive occurrence and multiplicity of function.

There has been the tendency in research to explore each of the functions of flavoproteins and iron sulphur clusters separately, but such functions can also combine to support a cycle.

It is proposed that adaptation of multiple functions into a cycle may have emerged through an adaptive evolutionary response – initially to the Great Oxidation Event, and then through endosymbiosis.  Perhaps this even offered the basis for the evolution of photosynthesis and respiration in an oxygen rich environment.

As electron transfer proteins they would enable long range electron transfer (which is used in photosynthesis, respiration, catalytic events). Electron transfer proteins contain redox-active prosthetic groups or “redox sites” where oxidation/reduction occurs. The most common redox sites contain metals such as hemes, iron-sulfur clusters, and copper centers but also include flavins, reducible disulfides, and quinones.  

Electron transfer (ET) is a very simple chemical process but closely governs the life on Earth. In nature, an immediate transfer of the electron(s) in photosynthetic reaction center converts light from the Sun to the forms of chemical energy and is stored in glucose or other types of organic compounds, ultimately supplying “food” for living creatures. In a class of blue-light receptor called cryptochrome found ubiquitously in plants and in animals, the process of ET is pivotal to generate the 24-hour life cycle of circadian rhythm and endogenously informs the body organism “time to sleep”. Furthermore, the ET reaction is also involved in repairing photo-damaged DNA and prevents some diseases like skin cancer. The role of ET in biology serves as an energy transmission and evolves the life using Sun power. Ting-fang He 2011. 

Read More…