Role of disulfide bonds in conformational stability and folding of 5′-deoxy-5′-methylthioadenosine phosphorylase II from the hyperthermophilic archaeon Sulfolobus solfataricus

► We investigated the role of disulfide bonds in stability and folding of SsMTAPII. ► We performed the spectroscopic characterization of SsMTAPII and its mutants. ► We carried out thermal and GdmCl-induced unfolding/refolding experiments. ► Chemical and thermal unfolding are reversible only under reducing conditions. ► Unfolding occurs with dissociation of the native hexamer into denatured monomers.