Featured Research

from universities, journals, and other organizations

Bio-Nanomachines: Proteins As Resistance Fighters

Date:
August 18, 2009
Source:
Max-Planck-Gesellschaft
Summary:
Friction limits the speed and efficiency of macroscopic engines. Is this also true for nanomachines? Researchers recently used laser tweezers to measure the friction between a single motor protein molecule and its track. The team found that also within our cells, motors work against the resistance of friction and are restrained in its operation—usually by far not as much though as their macroscopic counterparts.

Fluorescent image of single motor proteins (left): Motion of two diffusing kinesin molecules (green) on a microtubule (red) shown as a time series kymograph. Schematic (right): By dragging diffusing kinesin molecules with laser tweezers over a microtubule, the friction force between the motor and its microtubule track can be measured very precisely.
Credit: MPI-CBG, BIOTEC

Friction limits the speed and efficiency of macroscopic engines. Is this also true for nanomachines? A Dresden research team used laser tweezers to measure the friction between a single motor protein molecule and its track. The team found that also within our cells, motors work against the resistance of friction and are restrained in its operation—usually by far not as much though as their macroscopic counterparts.

These first experimental measurements of protein friction could help researchers to better understand key cellular processes such as cell division which is driven by such molecular machines. (Science, August 14, 2009)

Friction is the force that resists the relative motion of two bodies in contact. The same is true on the nanoscale: Molecular motors have to fight the friction created between them and their tracks. However, since the frictional forces acting on such motors had not been measured before, it was not known how they depend on the speed and the direction of motion.

Friction Slows Down Proteins

Scientists in Dresden at the Biotechnology Center (BIO-TEC) of the Technical University of Dresden and at the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) immobilized the molecular motor kinesin on a microsphere which was held by laser tweezers and dragged over its track, a so-called microtubule. In this manner, the friction force between the motor and its microtubule track was measured very precisely. "Just like for macroscopic machines, protein friction limits the speed and efficiency of the small bio-motors", says Erik Schäffer, group leader at the BIOTEC and Jonathon Howard, director and group leader at the MPI-CBG.

The researchers explain that the protein, in the absence of an energy source, takes eight nanometer (a millionth of a millimeter) wide "diffusive hops", corresponding to the length of the tubulin subunits that make up a microtubule. The motors step from one tubulin subunit to the adjacent one by forming a new bond with the microtubule filament as another bond is broken. When pulled by the tweezers, the energy released from these breaking bonds is lost as friction.

Efficient nanomachines

Protein friction also gives insight into the efficiency of kinesin. "About half of the energy from the motor’s fuel ATP is dissipated as friction between the motor and its substrate" Howard comments. Schäffer adds: "What remains after further dissipation inside the motor is used for mechanical work—the efficiency is usually much better than for man-made machines". The dissipated energy is eventually converted to heat, that contributes to the heating of our body. Thus, for example our muscles are partly heated by protein friction as the muscle motor proteins do their work.



Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Volker Bormuth, Vladimir Varga, Jonathon Howard, Erik Schäffer. Protein Friction Limits Diffusive and Directed Movements of Kinesin Motors on Microtubules. Science, 2009; 325 (5942): 870 DOI: 10.1126/science.1174923

Cite This Page:

Max-Planck-Gesellschaft. "Bio-Nanomachines: Proteins As Resistance Fighters." ScienceDaily. ScienceDaily, 18 August 2009. <www.sciencedaily.com/releases/2009/08/090814100101.htm>.
Max-Planck-Gesellschaft. (2009, August 18). Bio-Nanomachines: Proteins As Resistance Fighters. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2009/08/090814100101.htm
Max-Planck-Gesellschaft. "Bio-Nanomachines: Proteins As Resistance Fighters." ScienceDaily. www.sciencedaily.com/releases/2009/08/090814100101.htm (accessed October 2, 2014).

Share This



More Matter & Energy News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Japan Looks To Faster Future As Bullet Train Turns 50

Japan Looks To Faster Future As Bullet Train Turns 50

Newsy (Oct. 1, 2014) — Japan's bullet train turns 50 Wednesday. Here's a look at how it's changed over half a century — and the changes it's inspired globally. Video provided by Newsy
Powered by NewsLook.com
US Police Put Body Cameras to the Test

US Police Put Body Cameras to the Test

AFP (Oct. 1, 2014) — Police body cameras are gradually being rolled out across the US, with interest surging after the fatal police shooting in August of an unarmed black teenager. Duration: 02:18 Video provided by AFP
Powered by NewsLook.com
Raw: Japan Celebrates 'bullet Train' Anniversary

Raw: Japan Celebrates 'bullet Train' Anniversary

AP (Oct. 1, 2014) — A ceremony marking 50 years since Japan launched its Shinkansen bullet train was held on Wednesday in Tokyo. The latest model can travel from Tokyo to Osaka, a distance of 319 miles, in two hours and 25 minutes. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Robotic Hair Restoration

Robotic Hair Restoration

Ivanhoe (Oct. 1, 2014) — A new robotic procedure is changing the way we transplant hair. The ARTAS robot leaves no linear scarring and provides more natural results. Video provided by Ivanhoe
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins