1eq1: Difference between revisions

[[Image:1eq1.gif|left|200px]]

'''NMR STRUCTURE OF AN EXCHANGEABLE APOLIPOPROTEIN-MANDUCA SEXTA APOLIPOPHORIN-III'''

The high-resolution NMR structure of apolipophorin III from the sphinx moth, Manduca sexta, has been determined in the lipid-free state. We show that lipid-free apolipophorin III adopts a unique helix-bundle topology that has several characteristic structural features. These include a marginally stable, up-and-down helix bundle that allows for concerted opening of the bundle about "hinged" loops upon lipid interaction and buried polar/ionizable residues and buried interhelical H-bonds located in the otherwise hydrophobic interior of the bundle that adjust protein stability and facilitate lipid-induced conformational opening. We suggest that these structural features modulate the conformational adaptability of the lipid-free helix bundle upon lipid binding and control return of the open conformation to the original lipid-free helix-bundle state. Taken together, these data provide a structural rationale for the ability of exchangeable apolipoproteins to reversibly interact with circulating lipoprotein particles.

1EQ1 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Manduca_sexta Manduca sexta]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EQ1 OCA].  

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