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Structural Effect of Association on Protein Molecules in Partially Folded Intermediates

V. N. Uversky1,2* and A. L. Fink3

1Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (095) 924-0493; E-mail: uversky@vega.protres.ru

2Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia

3Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA

* To whom correspondence should be addressed.

Received August 25, 1997
Fluorescence and circular dichroism spectroscopy, small angle X-ray scattering and high performance liquid gel filtration have shown that oligomerization considerably affects the structural properties and conformational stability of partially folded intermediates of staphylococcal nuclease. Conformational transitions induced by different anions and association in the acid-unfolded protein are described. It is shown that association of non-native conformations of the protein molecule can be an additional structuring factor. The corresponding folding schemes and phase diagrams are suggested.
KEY WORDS: staphylococcal nuclease, partially-folded state, association, anion-induced forms