Kinetic analysis of salting activation of a subtilisin-like halophilic protease
Data
2009-02-01
Autores
Okamoto, Debora N. 
Kondo, Marcia Y.
Santos, Jorge A. N.
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The secreted extracellular subtilase SR5-3 from Halobacillus sp. bacterium, isolated from the high-salt environment of Thai fish sauce. was utilized as a model halophilic serine protease. the dependence of salt activation on the size and structure of substrates was evaluated assaying the enzyme with Suc-AAPF-MCA and with the Fluorescence Resonance Energy Transfer (FRET) peptide Abz-AAPFSSKQ-EDDnp. Solvent isotope effects (SIE) and the thermodynamic parameters for activation of the hydrolysis of Suc-AAPF-MCA and Abz-AAPFSSKQ-EDDnp by SR5-3 protease in the presence of salts were also performed. All the obtained results support the notion that the salting out effect is responsible for the halophilic character of SR5-3, and the magnitude of its hydrolytic activity is mainly derived from the improvement of catalytic and/or interaction steps depending on the nature and size of the substrates, principally if they occupy the substrate prime subsites. (C) 2008 Published by Elsevier B.V.
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Biochimica Et Biophysica Acta-proteins and Proteomics. Amsterdam: Elsevier B.V., v. 1794, n. 2, p. 367-373, 2009.