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

Reshma Bhowmick; Medicherla V. Jagannadham

doi:10.1007/s10930-006-9026-3

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

Reshma Bhowmick^*, Medicherla V. Jagannadham

^*Corresponding author for this work

Urology

Research output: Contribution to journal › Article › peer-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 (U_A-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 U_A-state. The anion-induced refolded state (I_A-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 language	English (US)
Pages (from-to)	399-410
Number of pages	12
Journal	Protein Journal
Volume	25
Issue number	6
DOIs	https://doi.org/10.1007/s10930-006-9026-3
State	Published - Sep 2006

Funding

We would like to thank Dr. Arvind M. Kayas-tha from School of Biotechnology, Faculty of Science, Banaras Hindu University for valuable suggestions. Authors duly acknowledge the Department of Biotechnology, Government of India for financial assistance and infrastructural facilities.

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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title = "Multiple intermediate conformations of jack bean urease at low pH: Anion-induced refolding",

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.",

keywords = "Acid-induced unfolded state, Anion-induced refolded state, GuHCl-induced unfolding, Jack bean urease, Thermal unfolding, Urea-induced unfolding",

author = "Reshma Bhowmick and Jagannadham, {Medicherla V.}",

note = "Funding Information: We would like to thank Dr. Arvind M. Kayas-tha from School of Biotechnology, Faculty of Science, Banaras Hindu University for valuable suggestions. Authors duly acknowledge the Department of Biotechnology, Government of India for financial assistance and infrastructural facilities.",

year = "2006",

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doi = "10.1007/s10930-006-9026-3",

language = "English (US)",

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T1 - Multiple intermediate conformations of jack bean urease at low pH

T2 - Anion-induced refolding

AU - Bhowmick, Reshma

AU - Jagannadham, Medicherla V.

N1 - Funding Information: We would like to thank Dr. Arvind M. Kayas-tha from School of Biotechnology, Faculty of Science, Banaras Hindu University for valuable suggestions. Authors duly acknowledge the Department of Biotechnology, Government of India for financial assistance and infrastructural facilities.

PY - 2006/9

Y1 - 2006/9

N2 - 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.

AB - 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.

KW - Acid-induced unfolded state

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KW - Jack bean urease

KW - Thermal unfolding

KW - Urea-induced unfolding

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

Abstract

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ASJC Scopus subject areas

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