The Cu,Zn superoxide dismutase isoenzymes of Xenopus laevis: Purification, identification of a heterodimer and differential heat sensitivity

Concetta R. Capo, Fabio Polticelli, Lilia Calabrese, M. Eugenia Schinina', Maria Teresa Carri', Giuseppe Rotilio

Research output: Contribution to journalArticle

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 pl, 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.

Original languageEnglish
Pages (from-to)1186-1193
Number of pages8
JournalBiochemical and Biophysical Research Communications
Volume173
Issue number3
DOIs
Publication statusPublished - Dec 31 1990

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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