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 Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>