Multiple intermediate conformations of jack bean urease at low pH: Anion-induced refolding

Reshma Bhowmick*, Medicherla V. Jagannadham

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Structural and functional characteristics of jack bean urease (JBU), a hexameric enzyme having identical subunits, were investigated under neutral as well as acidic conditions by using CD, fluorescence, ANS binding and enzyme activity measurements. At low pH and low ionic strength, JBU exists in a partially unfolded state (UA-state), having predominantly β structure and no tertiary interactions along with a strong ANS binding. Addition of salts like NaCl, KCl and Na2SO4 to the U A-state induces refolding resulting in structural propensities similar to that of native hexamer. Moreover, at low concentrations, GuHCl behaves like an anion by inducing refolding of the UA-state. The anion-induced refolded state (IA-state) is more stable than U A-state and the stability is nearly equal to that of the native protein against chemical-induced and thermal denaturation. Overall, these observations support a model of protein folding for a multimeric protein where certain conformations (ensembles of substates) of low energy prevail and populated under non-native conditions with different stability.

Original languageEnglish (US)
Pages (from-to)399-410
Number of pages12
JournalProtein Journal
Volume25
Issue number6
DOIs
StatePublished - Sep 2006

Keywords

  • Acid-induced unfolded state
  • Anion-induced refolded state
  • GuHCl-induced unfolding
  • Jack bean urease
  • Thermal unfolding
  • Urea-induced unfolding

ASJC Scopus subject areas

  • Analytical Chemistry
  • Bioengineering
  • Biochemistry
  • Organic Chemistry

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