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Demonstrating the uses of the novel gravitational force spectrometer to stretch and measure fibrous proteins.
MedLine Citation:
PMID:  21445050     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The study of macromolecular structure has become critical to the elucidation of molecular mechanisms and function. There are several limited, but important bioinstruments capable of testing the force dependence of structural features in proteins. Scale has been a limiting parameter on how accurately researchers can peer into the nanomechanical world of molecules, such as nucleic acids, enzymes, and motor proteins that perform life-sustaining work. Atomic force microscopy (AFM) is well tuned to determine native structures of fibrous proteins with a distance resolution on par with electron microscopy. However, in AFM force studies, the forces are typically much higher than a single molecule might experience (1, 2). Optical traps (OT) are very good at determining the relative distance between the trapped beads and they can impart very small forces (3). However, they do not yield accurate absolute lengths of the molecules under study. Molecular simulations provide supportive information to such experiments, but are limited in the ability to handle the same large molecular sizes, long time frames, and convince some researchers in the absence of other supporting evidence(2, 4). The gravitational force spectrometer (GFS) fills a critical niche in the arsenal of an investigator by providing a unique combination of abilities. This instrument is capable of generating forces typically with 98% or better accuracy from the femtonewton range to the nanonewton range. The distance measurements currently are capable of resolving the absolute molecular length down to five nanometers, and relative bead pair separation distances with a precision similar to an optical trap. Also, the GFS can determine stretching or uncoiling where the force is near equilibrium, or provide a graded force to juxtapose against any measured structural changes. It is even possible to determine how many amino acid residues are involved in uncoiling events under physiological force loads (2). Unlike in other methods where there is extensive force calibration that must precede any assay, the GFS requires no such force calibration (5). By complementing the strengths of other methods, the GFS will bridge gaps in understanding the nanomechanics of vital proteins and other macromolecules.
Authors:
James W Dunn; Douglas D Root
Publication Detail:
Type:  Journal Article     Date:  2011-03-19
Journal Detail:
Title:  Journal of visualized experiments : JoVE     Volume:  -     ISSN:  1940-087X     ISO Abbreviation:  J Vis Exp     Publication Date:  2011  
Date Detail:
Created Date:  2011-03-29     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101313252     Medline TA:  J Vis Exp     Country:  United States    
Other Details:
Languages:  eng     Pagination:  -     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, University of North Texas.
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