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Publication Abstract from PubMed

Previously, Lipase A from Bacillus subtilis was subjected to in vitro directed evolution using iterative saturation mutagenesis, with randomization sites chosen on the basis of the highest B-factors available from the crystal structure of the wild-type (WT) enzyme. This provided mutants that, unlike WT enzyme, retained a large part of their activity after heating above 65 degrees C and cooling down. Here, we subjected the three best mutants along with the WT enzyme to biophysical and biochemical characterization. Combining thermal inactivation profiles, circular dichroism, X-ray structure analyses and NMR experiments revealed that mutations of surface amino acid residues counteract the tendency of Lipase A to undergo precipitation under thermal stress. Reduced precipitation of the unfolding intermediates rather than increased conformational stability of the evolved mutants seems to be responsible for the activity retention.

Biophysical characterization of mutants of Bacillus subtilis lipase evolved for thermostability: Factors contributing to increased activity retention.,Augustyniak W, Brzezinska AA, Pijning T, Wienk H, Boelens R, Dijkstra BW, Reetz MT Protein Sci. 2012 Apr;21(4):487-97. doi: 10.1002/pro.2031. Epub 2012 Feb 29. PMID:22267088^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.