Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biological electron transfer captured in real time

04.03.2008
Two research teams led by Dr. Michael Verkhovsky and Prof. Mårten Wikström 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, muscle contraction, etc. The energy captured in cellular respiration is transduced to ATP in two phases. The role of the respiratory chain is to couple electron transfer to the translocation of positively charged protons across the membrane, so that the mitochondrial membrane (or the cell membrane in bacteria) becomes electrically polarised, just like charging up a battery. In the second phase, the voltage difference of the battery is used to drive the protons back across the membrane, coupled to the synthesis of ATP by very special molecular machinery.

The first enzyme complex of the respiratory chain is called Complex I. High-energy electrons are fed into this complex in the form of a reduced coenzyme, NADH (nicotinamide adenine dinucleotide), which is oxidised to NAD+ having donated its two electrons. After this, the electrons are transferred along several protein-bound iron/sulphur centres in Complex I until they reach their destination, a molecule of ubiquinone, which is thus reduced to ubiquinol. This reaction, as catalysed by Complex I, is linked to proton translocation across the membrane and thus leads to "charging the battery". At a later stage ubiquinol donates its electrons further in the respiratory chain (ultimately to oxygen), by which it is oxidised back to ubiquinone to allow continuation of Complex I function.

For more information, please, contact Professor Mårten Wikström,
tel. +358 9 191 58000. Email: marten.wikstrom(at)helsinki.fi.

Kirsikka Mattila | alfa
Further information:
http://www.helsinki.fi

More articles from Physics and Astronomy:

nachricht Levitating objects with light
19.03.2019 | California Institute of Technology

nachricht Stellar cartography
19.03.2019 | Leibniz-Institut für Astrophysik Potsdam

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

Im Focus: Sensing shakes

A new way to sense earthquakes could help improve early warning systems

Every year earthquakes worldwide claim hundreds or even thousands of lives. Forewarning allows people to head for safety and a matter of seconds could spell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Levitating objects with light

19.03.2019 | Physics and Astronomy

New technique for in-cell distance determination

19.03.2019 | Life Sciences

Stellar cartography

19.03.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>