The two Cu,Zn superoxide dismutases from the amphibian Xenopus laevis (denoted XSODA and XSODB) display different heat sensitivities, XSODA being more thermolabile than XSODB. In this study, we have investigated the contribution of a free cysteine residue located close to the subunit interface of XSODA to its lower thermal stability. We have found that mutation of residue Cys 150 to Ala in XSODA makes the thermal stability of this enzyme comparable to that of the wild-type XSODB isoenzyme, while the introduction of a cysteine residue in the same position of XSODB renders this enzyme variant much more heat-sensitive. Differential scanning calorimetry experiments showed that XSODA has a melting temperature about 8.5 degrees C lower than that of XSODB. On the contrary, the melting temperature of XSODACys150Ala is very close to that of XSODB, while the melting temperature of XSODBSer150Cys is even lower than that of wild-type XSODA. These data indicate that the free cysteine residue present in XSODA affects not only the reversibility of unfolding of the enzyme but also its conformational stability. We suggest that the large effect of the Cys 150 residue on XSODA stability might be due to incorrect disulfide bond formation or disulfide bond interchange during heat-induced unfolding rather than to alteration of the interaction between the enzyme subunits.

Bonaccorsi di Patti, M., Carrì, M., Gabbianelli, R., Da Gai, R., Volpe, C., Giartosio, A., et al. (2000). A free cysteine residue at the dimer interface decreases conformational stability of Xenopus laevis copper,zinc superoxide dismutase. ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, 377(2), 284-289.

A free cysteine residue at the dimer interface decreases conformational stability of Xenopus laevis copper,zinc superoxide dismutase

Rotilio G;Battistoni A
2000-05-15

Abstract

The two Cu,Zn superoxide dismutases from the amphibian Xenopus laevis (denoted XSODA and XSODB) display different heat sensitivities, XSODA being more thermolabile than XSODB. In this study, we have investigated the contribution of a free cysteine residue located close to the subunit interface of XSODA to its lower thermal stability. We have found that mutation of residue Cys 150 to Ala in XSODA makes the thermal stability of this enzyme comparable to that of the wild-type XSODB isoenzyme, while the introduction of a cysteine residue in the same position of XSODB renders this enzyme variant much more heat-sensitive. Differential scanning calorimetry experiments showed that XSODA has a melting temperature about 8.5 degrees C lower than that of XSODB. On the contrary, the melting temperature of XSODACys150Ala is very close to that of XSODB, while the melting temperature of XSODBSer150Cys is even lower than that of wild-type XSODA. These data indicate that the free cysteine residue present in XSODA affects not only the reversibility of unfolding of the enzyme but also its conformational stability. We suggest that the large effect of the Cys 150 residue on XSODA stability might be due to incorrect disulfide bond formation or disulfide bond interchange during heat-induced unfolding rather than to alteration of the interaction between the enzyme subunits.
15-mag-2000
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore BIO/10 - BIOCHIMICA
English
Con Impact Factor ISI
Xenopus laevis; Superoxide Dismutase; Animals; Thermodynamics; Cysteine; Enzyme Stability; Electron Spin Resonance Spectroscopy; Dimerization; Temperature; Time Factors; Calorimetry, Differential Scanning; Protein Conformation
Bonaccorsi di Patti, M., Carrì, M., Gabbianelli, R., Da Gai, R., Volpe, C., Giartosio, A., et al. (2000). A free cysteine residue at the dimer interface decreases conformational stability of Xenopus laevis copper,zinc superoxide dismutase. ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, 377(2), 284-289.
Bonaccorsi di Patti, M; Carrì, M; Gabbianelli, R; Da Gai, R; Volpe, C; Giartosio, A; Rotilio, G; Battistoni, A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/52696
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