The three Cu,Zn superoxide dismutase electromorphs of the amphibian Xenopus laevis were purified by an original procedure. N-terminal sequence analysis demonstrated that they are two different homodimers (AA and BB) and a hybrid heterodimer (AB), arising from the co-expression of duplicated genes. The three forms have the same pI, same enzyme activity and EPR spectra, but different heat-sensitivity, form BB being more resistant than form AA, with form AB showing intermediate sensitivity. Thermostability of BB and the control bovine enzyme was enhanced by a tenfold increase in protein concentration. It is suggested that the higher heat sensitivity of the AA isoenzyme is related to the presence of an extra Cys residue and to an easier dissociation of the protein dimer into monomers.
Capo, C.r., Polticelli, F., Calabrese, L., Schinina, M., Carri', M.t., Rotilio, G. (1990). The Cu,Zn superoxide dismutase isoenzymes of Xenopus laevis: purification, identification of a heterodimer and differential heat sensitivity. BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 173(3), 1186-1193.
The Cu,Zn superoxide dismutase isoenzymes of Xenopus laevis: purification, identification of a heterodimer and differential heat sensitivity
CAPO, CONCETTA ROSA;CALABRESE, LEONARDO;CARRI', MARIA TERESA;ROTILIO, GIUSEPPE
1990-12-31
Abstract
The three Cu,Zn superoxide dismutase electromorphs of the amphibian Xenopus laevis were purified by an original procedure. N-terminal sequence analysis demonstrated that they are two different homodimers (AA and BB) and a hybrid heterodimer (AB), arising from the co-expression of duplicated genes. The three forms have the same pI, same enzyme activity and EPR spectra, but different heat-sensitivity, form BB being more resistant than form AA, with form AB showing intermediate sensitivity. Thermostability of BB and the control bovine enzyme was enhanced by a tenfold increase in protein concentration. It is suggested that the higher heat sensitivity of the AA isoenzyme is related to the presence of an extra Cys residue and to an easier dissociation of the protein dimer into monomers.Questo articolo è pubblicato sotto una Licenza Licenza Creative Commons