Conformational Changes in Guanylate Kinase Studied by Osmotic Stress and SANS

 

Christopher Stanley1, Susan Krueger1, V. Adrian Parsegian2, and Donald C. Rau2

 

1NIST Center for Neutron Research, Gaithersburg, MD; 2NICHD, National Institutes of Health, Bethesda, MD

 

Protein conformational changes induced by ligand binding are accompanied by a change in the number of water molecules sequestered in pockets, cavities, and grooves.  The significance of hydration to protein-ligand interactions has been illustrated using the osmotic stress technique.  We are using small-angle neutron scattering (SANS) coupled with the osmotic stress technique to directly probe the connection between protein structural change and thermodynamics for guanylate kinase.  We chose this enzyme because it is known to undergo a large conformational change upon binding the ligand GMP.  We are able to follow this conformational change using SANS to determine the radius of gyration, Rg, and the pair-distribution function, P(R), and now we are investigating protein mechanics by using osmotic stress to induce the conformational change in the absence of ligand.  This should offer new opportunities for protein structure research by allowing the energetics of the conformational change to be measured apart from the ligand binding energy.

 

Christopher Stanley

Mentor: Susan Krueger

 

NIST Center for Neutron Research

Materials Science and Engineering Laboratory

Bldg. 235 / Rm. E18

Mail Stop 8562

 

Telephone #: 301-975-8829

FAX #: 301-921-9847

Email: cstanley@nist.gov

 

Sigma Xi member: No

 

Category: Biology