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Int J Biol Macromol. 2018 Apr 1;109:1039-1044. doi: 10.1016/j.ijbiomac.2017.11.081. Epub 2017 Nov 22.

Thermodynamic investigation of an alkaline protease from Aspergillus tamarii URM4634: A comparative approach between crude extract and purified enzyme.

Author information

1
Northeast Biotechnology Network, Federal Rural University of Pernambuco, Dom Manoel de Medeiros, s/n, Dois Irmãos, 52171-900 Recife, PE, Brazil.
2
Department of Civil, Chemical and Environmental Engineering, Pole of Chemical Engineering, Genoa University, Via Opera Pia, 15, 16145 Genova, Italy.
3
Northeast Biotechnology Network, Federal Rural University of Pernambuco, Dom Manoel de Medeiros, s/n, Dois Irmãos, 52171-900 Recife, PE, Brazil; Academic Unit of Garanhuns, Federal Rural University of Pernambuco, Av. Bom Pastor, s/n, Boa Vista, 55296-901 Garanhuns, PE, Brazil. Electronic address: portots@yahoo.com.br.

Abstract

The thermostable crude proteolytic extract and purified protease produced by Aspergillus tamarii URM4634 were investigated at different temperatures. The activity results were used to estimate the activation energy of the hydrolysis reaction catalyzed by crude extract and purified protease (E*=34.2 and 16.2kJ/mol) as well as the respective standard enthalpy variations of reversible enzyme unfolding (ΔH°u=31.9 and 13.9kJ/mol). When temperature was raised from 50 to 80°C in residual activity tests, the specific rate constant of crude proteolytic extract thermoinactivation increased from 0.0072 to 0.0378min-1, while that of purified protease from 0.0099 to 0.0235min-1. These values, corresponding to half-life decreases from 96.3 to 18.3min and from 70.0 to 29.5min, respectively, enabled us to estimate the activation energy (E*d=49.7 and 28.8kJ/mol), enthalpy (ΔH*d=47.0 and 26.1kJ/mol), entropy (ΔS*d=-141.3 and -203.1J/molK) and Gibbs free energy (92.6≤ΔG*d≤96.6kJ/mol and 91.8≤ΔG*d≤98.0kJ/mol) of thermoinactivation. Such values suggest that this protease, which proved to be highly thermostable in both forms, could be profitably exploited in industrial applications. To the best of our knowledge, this is the first comparative study on thermodynamic parameters of a serine protease produced by Aspergillus tamarii URM4634.

KEYWORDS:

Aspergillus tamarii URM4634; Serine protease; Thermodynamic parameters

PMID:
29155158
DOI:
10.1016/j.ijbiomac.2017.11.081
[Indexed for MEDLINE]
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