Reactivation and refolding of a partially folded creatine kinase modified by 5,5 '-dithio-bis(2-nitrobenzoic acid)

Creatine kinase with its thiol groups modified by 5,5'-dithio-bis(2-nitrobe nzoic acid) has been shown to be partially folded in a monomeric state usin g fluorescence, circular dichroism, proteolysis, and size exclusion chromat ography studies. In the presence of DTT, the partially folded modified crea tine kinase can be reactivated and refolded following a biphasic course, su ggesting the existence of a monomeric intermediate during the folding of CK . The results provide evidence for our previously suggested model of the re folding pathway of urea-denatured creatine kinase. (C) 1999 Academic Press.