Premium
Bile salt hydrolase, the member of Ntn‐hydrolase family: Differential modes of structural and functional transitions during denaturation
Author(s) -
Kumar R. Suresh,
Suresh C. G.,
Brannigan James A.,
Dodson Guy G.,
Gaikwad Sushama M.
Publication year - 2007
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216540701245014
Subject(s) - chemistry , denaturation (fissile materials) , hydrolase , circular dichroism , enzyme , molten globule , bifidobacterium longum , protein tertiary structure , conformational change , active site , biochemistry , stereochemistry , fermentation , nuclear chemistry , bifidobacterium , lactobacillus
Conformational transitions and functional stability of the bile salt hydrolase (BSH; cholylglycine EC: 3.5.1.24) from Bifidobacterium longum (BlBSH) cloned and expressed in E. coli were studied under thermal, chemical and pH‐mediated denaturation conditions using fluorescence and CD spectroscopy. Thermal and Gdn‐HCl‐mediated denaturation of BlBSH is a multistep process of inactivation and unfolding. The inactivation and unfolding of the enzyme was found to be irreversible. Enzyme activity seems sensitive to even minor conformational changes at the active site. Thermal denaturation as such did not result in any insoluble protein aggregates. However, on treating with 0.25 ‐ 1 M Gdn‐HCl the enzyme showed increasing aggregation at temperatures of 40 ‐ 55°C indicating more complex structural changes taking place in the presence of chemical denaturants. The enzyme secondary structure was still intact at acidic pH (pH 1 ‐ 3). The perturbation in the tertiary structure at the acidic pH was detected through freshly formed solvent exposed hydrophobic patches on the enzyme. These changes could be due to the formation of an acid‐induced molten globule‐like state.IUBMB Life, 59: 118‐125, 2007