Effect of organic solvents on the activity and stability of an extracellular protease secreted by the haloalkaliphilic archaeon Natrialba magadii
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The effect of various organic solvents on the activity and stability of an extracellular protease produced by the haloalkaliphilic archaeon Natrialba magadii was tested. This protease was active and stable in aqueous-organic solvent mixtures containing 1.5 M NaCl and glycerol, dimethylsulfoxide (DMSO), N,N-dimethyl formamide, propylenglycol, and dioxane. Among the solvents tested, DMSO, propylenglycol, and glycerol were effective in preserving enzyme stability in suboptimal NaCl concentrations. The stabilizing effect of DMSO on this haloalkaliphilic protease was more efficient at pH 8 than at pH 10, suggesting that DMSO may not substitute for salt to allow halophilic proteins to withstand the effect of high pH values. These results show that Nab. magadii extracellular protease is a solvent tolerant enzyme and suggest a potential application of this haloalkaliphilic protease in aqueous-organic solvent biocatalysis.
KeywordsProtease stability Organic solvent Haloarchaea Natrialba magadii
This work was supported by research grants from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional de Mar del Plata (UNMDP), Argentina. D. M. Ruiz is a graduate student supported by a CONICET fellowship. The authors acknowledge Dr. C. A. Studdert, Dr. R. D. Conde, and Dr. G. R. Daleo for the critical reading of the manuscript.
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