Conformational change

From Wikipedia, the free encyclopedia

In molecular biology, a protein may change its shape in order to undertake a new function; each possible shape is called a conformation, and a transition between them is called a conformational change. Conformation change is sometimes also known as protein motion, of which moving proteins that require ATP to change shape are a distinct subset. The precise distinction between protein motion and conformational change can be subtle, in that protein motions can also sometimes be said to include changes in protein shape due to the movement of a flexible linker that would not normally be classified as conformational change. In this sense, conformation change may be regarded as a subset of protein motion, although for technical and other reasons most experimentally studied examples of protein motion are also examples of conformation change.

In conformation change, it is usually the tertiary structure of the molecule that is affected, as it is usually this structure that determines a protein's function.

A conformational change may be induced with many scenarios, such as a change in temperature, pH, or the binding of a ligand to a receptor.

Recently, second-harmonic generation (SHG), a nonlinear optical technique, has been applied to the study of conformational change in proteins. In this method, a second-harmonic-active probe is placed at a site that undergoes motion in the protein by mutagenesis or non-site-specific attachment, and the protein is adsorbed or specifically immobilized to a surface. A change in protein conformation produces a change in the net orientation of the dye relative to the surface plane and therefore the intensity of the second harmonic beam. In a protein sample with a well defined orientation, the tilt angle of the probe can be quantitatively determined, in real space and real time. Second-harmonic-active unnatural amino acids can also be used as probes.

[edit] External Links

• Book Chapter on Protein Motions from website of RH Austin [1] at Princeton University
• Frauenfelder, H. New looks at protein motions Nature 338, 623 - 624 (20 April 1989).
• Detection of Protein Conformational Change by Optical Second-Harmonic Generation
• Biodesy

[edit] See Also

• The Database of Macromolecular Motions (molmovdb)