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Effect of acetonitrile on Cynara cardunculus L. cardosin A stability |
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| Authors: | Shnyrova Anna V Oliveira Claudia S Sarmento Ana C Barros Marlene T Zhadan Galina G Roig Manuel G Shnyrov Valery L |
| Affiliation: | aDepartamento de Bioquímica y Biología Molecular, Universidad de Salamanca, 37007 Salamanca, Spain bDepartamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro, Portugal cCentro de Biologia Celular, Universidade de Aveiro, 3810-193 Aveiro, Portugal dUniversidade Católica Portuguesa, Centro Regional das Beiras, Pólo de Viseu, 3504-505 Viseu, Portugal eDepartamento de Química Física, Universidad de Salamanca, 37008 Salamanca, Spain |
| Abstract: | The kinetics of the structural changes affecting cardosin A, a plant aspartic proteinase (AP) from Cynara cardunculus L., in the presence of a mixture of acetonitrile (AN) in water (W) was studied. Incubation of cardosin A with 10% (v/v) AN resulted in a gradual increase in protein helicity, accompanied by changes in the tertiary structure, seen by changes in the intrinsic fluorescence of tryptophan. Differential scanning calorimetry (DSC) revealed that the temperature of denaturation of cardosin A decreased upon the addition of AN. With longer incubation times, the small chain of cardosin A denatured completely, consequent exposure of the single tryptophan residue accounting well for the observed spectral shift intrinsic fluorescence of the protein. Enzymatic activity assays demonstrated that the kinetically determined unfolding of the small chain of cardosin A does not result in loss of the activity of this enzyme. |
| Keywords: | Cardosin A Protein stability Low organic medium catalysis Water–acetonitrile mixture Differential scanning calorimetry |
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