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Licensed Unlicensed Requires Authentication Published by De Gruyter June 1, 2005

Osmolytes as Modulators of Conformational Changes in Serpins

  • Michelle K.M. Chow , Glyn L. Devlin and Stephen P. Bottomley
From the journal Biological Chemistry

Abstract

Protein misfolding and aggregation play an integral role in many diseases. The misfolding of the serpin (SERine Proteinase INhibitor) α1-antitrypsin results in the accumulation of insoluble polymers within hepatocytes and α1-antitrypsin deficiency in plasma, predisposing patients to liver cirrhosis and emphysema. We have examined the effect of three naturally occurring osmolytes, sarcosine, glycine betaine and trimethylamine Noxide, on conformational changes in α1-antitrypsin. All three solutes protected native α1-antitrypsin against thermally induced polymerisation and inactivation in a concentrationdependent manner. Further spectroscopic analysis showed that sarcosine stabilises the native conformation of α1-antitrypsin, thus hindering its conversion to an intermediate state and subsequent polymerisation. On refolding in the presence of sarcosine, α1-antitrypsin formed a heterogeneous population, with increasing proportions of molecules adopting an inactive conformation in higher concentrations of the osmolyte. These data show that sarcosine can be used to prevent abnormal structural changes in native α1-antitrypsin, but is ineffective in facilitating the correct folding of the protein. The implications of these results in the context of conformational changes and states adopted by α1-antitrypsin are discussed.

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Published Online: 2005-06-01
Published in Print: 2001-11-13

Copyright © 2001 by Walter de Gruyter GmbH & Co. KG

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