We have identified intrinsically unstructured C-terminus of a Bacillus lipase. In an effort to understand the possible
role of this C-terminus unstructured region, 10, 20 and 30 amino acids were serially deleted from C-terminal region
of the lipase. The catalytic properties of wild type and resulted truncated enzymes were compared. Deletion of 10 amino
acids from C-terminus region resulted in decrease in transcription of lipase, specific enzyme activity and extracellular secretion
of lipase in comparison to wild type while no effect on lipase aggregation was observed. Negligible activity was
observed upon deletion of 20 amino acids. The homology model of the protein demonstrated that the tertiary structure of
the protein was held together by these C-terminus residues due to six critically placed hydrogen bonds. Therefore Cterminus
was essential for the tertiary structure and enzyme activity of lipase. Due to structural flexibility and plasticity
originating from the lack of a definite-ordered 3D structure, such disordered regions might represent a major functional
advantage for proteins.
Keywords: Aggregation, catalytic properties, C-terminus deletion, homology modeling, lipase.
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