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An esterase from Thermus thermophilus HB27 with hyper-thermoalkalophilic properties: Purification, characterisation and structural modelling
[Display omitted] ► A membrane-associated esterase (E34Tt) was detected in Thermus thermophilus HB27. ► E34Tt was purified, and identified by peptide mass fingerprinting. ► CHAPS was essential for activity and stability. E34Tt has preference for C10 esters. ► High thermophilicity; optimal temperatur...
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Published in: | Journal of molecular catalysis. B, Enzymatic Enzymatic, 2011-07, Vol.70 (3), p.127-137 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | [Display omitted]
► A membrane-associated esterase (E34Tt) was detected in
Thermus thermophilus HB27. ► E34Tt was purified, and identified by peptide mass fingerprinting. ► CHAPS was essential for activity and stability. E34Tt has preference for C10 esters. ► High thermophilicity; optimal temperature was >80
°C and
t
1/2 at 85
°C
>
135
min. ► A theoretical structural model was proposed using a prolyl oligopeptidase as template.
A membrane-associated esterase (E34Tt) was detected in
Thermus thermophilus HB27. The enzyme was purified to homogeneity in a three-step protocol. Detergent (CHAPS) above the CMC was found to be essential to solubilise the enzyme from cell membranes as well as for maintaining activity and stability.
By using mass fingerprinting, peptides were found to share identity with the YP_004875 protein, which was annotated as putative esterase in the genome analysis of
T. thermophilus HB27, although experimental evidence was lacking. No homology was detected with any known lipase or esterase. However, a comparison with the high-scored sequences from a BLASTp search identified the consensus sequence for lipases/esterases between amino acids 157 and 161 (Gly-Cys-Ser
159-Ala-Gly). Further inhibition assays with E600 confirmed that Ser
159 was involved in the catalytic mechanism.
The monomeric enzyme had a molecular mass of 34
kDa and exhibited esterase activity with preference for medium chain-length esters (C10). E34Tt was noticeable for its high thermal stability; the optimal reaction temperature was higher than 80
°C and the half-life of thermal inactivation at 85
°C was 135
min, which makes it even more thermostable than some hyperthermophilic esterases. These properties convert E34Tt into a very attractive enzyme for biotechnological purposes.
A theoretical structural model was constructed using as template a prolyl oligopeptidase from
Sus scrofa, and a putative catalytic triad (Ser
159, Glu
255 and His
293) with high similarity to the template was identified. |
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ISSN: | 1381-1177 1873-3158 |
DOI: | 10.1016/j.molcatb.2011.02.017 |