James L
05-13-2006, 12:51 PM
Some excerpts, that may be of interest, from "The Biological Frontier of Physics," by Rob Phillips and Stephen R. Quake, in Physics Today (May 2006).
Molecular machines are the basis of life. DNA, a long molecule that encodes the blueprints to create an organism, may be life's information storage medium, but it neds a bevy of machines to read and translate that information into action. The cell's nanometer-scale machines are mostly protein molecules, although a few are made from RNA, and they are capable of surprisingly complex manipulations. They perform almost all the important active tasks in the cell: metabolism, reproduction, response to changes in the environment, and so forth. They are incredibly sophisticated, and they, not their manmade counterparts, represent the pinnacle of nanotechnology. Yet scientists have no general theory for their assembly or operation. The basic physical principles are individually well understood; what is lacking is a framework that combines the elegance of abstraction with the power of prediction.
(Paragraph omitted.)
How much can one molecule do? Consider, for example, ATP (adenosine triphosphate) synthase. This macromolecular assembly, only about 10 nanometers on a side, is an essential part of the cellular factory that produces ATP, the universal energy currency of life. We will not get into the details of the biological role of ATP synthase in the cell, but consider merely what it is capable of doing in isolation: It is a rotary motor. In the presence of a proton gradient, this remarkable machine turns a spindle as it adds phosphate groups to molecules of adenosine diphosphate to produce ATP. [see article's ref. 2] And every day ... the cells in your body perform this phosphate-addition reaction to produce roughly your body weight in ATP molecules.
But that is not all: ATP synthase can run in reverse. It can consume ATP, and with each ATP molecule that is hydrolyzed, the central shaft of ATP synthase turns by 120 degrees, directly converting chemical to mechanical energy. ... with absolute thermodynamic efficiencies of up to 90%. Despite the tremendous strides made in nanotechnology, no device of similar functionality can yet be fabricated with inorganic materials.
(Rob Phillips is a professor of applied physics and mechanical engineering at CalTech. Stephen Quake is a Howard Hughes Medical Institute investigator, and is a professor of bioengineering with a courtesy appointment in the applied physics department at Stanford University.)
This is basic science that is not only the science behind Protein Power, it is science that underlies all human metabolism.
So don't let any diet book mislead you into thinking that protein is not important. Adequate, high-quality, complete protein is very important. Make sure you eat enough of it!
(Above quote from me, not from Phillips and Quake. :) )
The link below is to an animation of the rotary stepping motion of ATP synthase.
Note 1: This is about a 3.5 MB download, and it is basic science not Hollywood. So you may want to skip it unless you have a broadband connection or are really interested.
Note 2: The "backwards mistake" (due to a thermal fluctuation) occurs just prior to the 50 second mark on the chart in the left half of the browser window.
http://www.k2.phys.waseda.ac.jp/F1movies/F1Step.htm (c. 3.5 MB)
.
Molecular machines are the basis of life. DNA, a long molecule that encodes the blueprints to create an organism, may be life's information storage medium, but it neds a bevy of machines to read and translate that information into action. The cell's nanometer-scale machines are mostly protein molecules, although a few are made from RNA, and they are capable of surprisingly complex manipulations. They perform almost all the important active tasks in the cell: metabolism, reproduction, response to changes in the environment, and so forth. They are incredibly sophisticated, and they, not their manmade counterparts, represent the pinnacle of nanotechnology. Yet scientists have no general theory for their assembly or operation. The basic physical principles are individually well understood; what is lacking is a framework that combines the elegance of abstraction with the power of prediction.
(Paragraph omitted.)
How much can one molecule do? Consider, for example, ATP (adenosine triphosphate) synthase. This macromolecular assembly, only about 10 nanometers on a side, is an essential part of the cellular factory that produces ATP, the universal energy currency of life. We will not get into the details of the biological role of ATP synthase in the cell, but consider merely what it is capable of doing in isolation: It is a rotary motor. In the presence of a proton gradient, this remarkable machine turns a spindle as it adds phosphate groups to molecules of adenosine diphosphate to produce ATP. [see article's ref. 2] And every day ... the cells in your body perform this phosphate-addition reaction to produce roughly your body weight in ATP molecules.
But that is not all: ATP synthase can run in reverse. It can consume ATP, and with each ATP molecule that is hydrolyzed, the central shaft of ATP synthase turns by 120 degrees, directly converting chemical to mechanical energy. ... with absolute thermodynamic efficiencies of up to 90%. Despite the tremendous strides made in nanotechnology, no device of similar functionality can yet be fabricated with inorganic materials.
(Rob Phillips is a professor of applied physics and mechanical engineering at CalTech. Stephen Quake is a Howard Hughes Medical Institute investigator, and is a professor of bioengineering with a courtesy appointment in the applied physics department at Stanford University.)
This is basic science that is not only the science behind Protein Power, it is science that underlies all human metabolism.
So don't let any diet book mislead you into thinking that protein is not important. Adequate, high-quality, complete protein is very important. Make sure you eat enough of it!
(Above quote from me, not from Phillips and Quake. :) )
The link below is to an animation of the rotary stepping motion of ATP synthase.
Note 1: This is about a 3.5 MB download, and it is basic science not Hollywood. So you may want to skip it unless you have a broadband connection or are really interested.
Note 2: The "backwards mistake" (due to a thermal fluctuation) occurs just prior to the 50 second mark on the chart in the left half of the browser window.
http://www.k2.phys.waseda.ac.jp/F1movies/F1Step.htm (c. 3.5 MB)
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