Printer Friendly

Lone protein molecule could tip this scale.

Physicists developing exquisitely fine-tuned scales for weighing tiny objects have reached an important milestone--a device sensitive enough to detect individual molecules of biologically active proteins.

To make their protein scale, Michael L. Roukes of the California Institute of Technology in Pasadena and his colleagues fashioned bacterium-size bridges of silicon carbide, a durable semi-conducting compound, onto microchips. Then, they chilled those bridges in a vacuum chamber to temperatures near absolute zero and set them vibrating by means of electromagnetic forces.

By exposing the tuning fork-like devices momentarily to a spray of xenon atoms, the researchers found that the instrument responded--with a slight slowing of its vibrational frequencies--to as few as 30 atoms of xenon settling onto it.

The xenon atoms' collective mass is so small that the scientists had to resort to a little-known unit of measure--the zeptogram--to describe it. At 7 zeptograms, or billionths of a trillionth of a gram, this mass is comparable to that of many small proteins important in functions such as cell-to-cell signaling, Roukes notes.

Such on-chip bridges could prove valuable for investigating the vast and little-charted realm of protein behavior, or proteomics, says Roukes (SN: 12/13/03, p. 371).

The zeptogram-magnitude measurement also moves the team closer to its ultimate goal: a chip-based device capable of weighing a single hydrogen atom. That pursuit promises to open new linguistic territory as well: A hydrogen atom weighs about 1 yoctogram--a thousandth of a zeptogram.--P.W.
COPYRIGHT 2005 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2005, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:METROLOGY
Publication:Science News
Article Type:Brief Article
Geographic Code:1USA
Date:Apr 9, 2005
Previous Article:Tense encounters drive a nanomotor.
Next Article:Tending Fire: Coping with America's Wildland Fires.

Related Articles
A raison d'etre for heat-shock proteins.
Liquid crystal bridges silk-spinning gap.
Cyclosporin-protein complex controls genes.
Water, water everywhere: subtly shaping protein structure and function.
Whey protein separation technique results in improved commercial properties.
Whey protein separation technique improves protein properties.
RNA world gets support as prelife scenario. (Science News of the week).
No assembly required: DNA brings carbon nanotube circuits in line.
Sensor measures mass of one DNA molecule.
Size matters: biosensors behave oddly when very small.

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters