Chaperonin 60 (GroEL) and chaperonin 10 (GroES) belong to the ubiquitous family of heat-shock molecular chaperones found in prokaryotes and in eukaryotic organelles. The chaperonins assist the folding of nascent, organelle-imported or stress-destabilized polypeptides. In vitro, purified GroEL together with purified GroES in the presence of Mg-ATP facilitate refolding and reactivation of denatured proteins, e.g., the photosynthetic enzyme rubisco and the mitochondrial enzyme rhodanese.The folding activity of a 1:1 molar mixture of GroEL and GroES was tested using urea-denatured rhodanese. At least 2-fold reactivation of rhodanese over the spontaneous reactivation was obtained.
