Crystallization and preliminary X-ray crystallographic investigations on several thermostable forms of a Bacillus subtilis lipase.
Bacillus subtilis lipase loses activity above pH 10.5 and below pH 6.0. However, at low pH, i.e. below pH 5.0, the lipase acquires remarkable thermostability. Activity was unaltered for 2 h at 323 K at pH 4.0-5.0, although at pH values above 7.0 the activity was lost rapidly within minutes. Circular-dichroism studies indicate significant changes in the tertiary structure of the lipase, whereas the secondary-structural content remained unaltered. To elucidate the structural basis of the enhanced thermostability, three different forms have been crystallized at low pH along with three crystal forms of two thermostable mutants obtained using a directed-evolution approach.
Rajakumara
Eerappa
E
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
Acharya
Priyamvada
P
Ahmad
Shoeb
S
Shanmugam
Vellaiah M
VM
Rao
Nalam M
NM
Sankaranarayanan
Rajan
R
D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D003460:Crystallization; D018360:Crystallography, X-Ray; D019020:Directed Molecular Evolution; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000737:chemistry* / Q000235:genetics; D017354:Point Mutation / Q000235:genetics
D001426:Bacterial Proteins; C079999:LipA protein, Bacteria; D008049:Lipase