Biological electron transfer captured in...( Two research teams led by Dr. Michae...)

Two research teams led by Dr. Michael Verkhovsky and Prof. Mrten Wikstrm of the Institute of Biotechnology of the University of Helsinki have for the first time succeeded in monitoring electron transfer by Complex I in real time. In the future, this work might, for example, have medical relevance, because most of the maternally inherited so-called mitochondrial diseases are caused by dysfunction of Complex I.

This achievement required developing and building of a special device by which the enzyme-catalysed electron transfer could be captured at different time points by stopping the reaction at liquid nitrogen temperatures, on a microsecond (one millionth of a second) time scale. The electrons are very small elementary particles, which is why their transfer is very fast. This work is published this week in the prestigious journal of the American National Academy of Sciences (Proc. Natl. Acad. Sci.). The results give certain hints of the function of Complex I at the molecular level.

Electron transfer is central to many chemical reactions in the cell. It has particular functional importance in cell respiration, which in eukaryotes takes place in the inner mitochondrial membrane, and in the cell membrane of prokaryotes. In cellular respiration molecules stemming from food are oxidised to carbon dioxide, and the electrons liberated in the process are "fed" into the so-called respiratory chain, which consists of three successive membrane-bound enzyme complexes, finally to react with the oxygen we breathe, which is reduced to water using these electrons.

The purpose of electron transfer in cellular respiration is to release the major part of the energy of foodstuffs and to conserve it in a suitable form, ATP (adenosine triphosphate), which the cell may use in its energy-requiring reactions (e.g. biosynthesis, active transport, mechanical work), which are essential e.g. during fetal development and growth, in neural and kidney function, m
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