Molecular chaperones are proteins that assist other proteins to fold correctly, and are also involved in disaggregation, aggregation avoidance and others. Chaperones belonging to the ClpB/Hsp100 family are specialized disaggregating machines that, in cooperation with the molecular chaperones of the Hsp70 system, perform disaggregation of proteins after stress processes. In a major data mining effort to identify all molecular chaperones in the SUCEST (Sugarcane EST Project), many Hsp100-related clusters were encountered (Borges et al., 2001, Gen. Mol. Biol. 24, 85-92), and a specific target was selected in order to develop structural and functional studies. This specific target, the sugarcane Hsp101 (scHsp101) protein, was expressed and purified, resulting in a protein more than 95% pure. Circular dichroism analysis showed that scHsp101 present high alpha-helical content, such as described to other Hsp101/ClpB proteins, and the analysis of the fluorescence emission from its tryptophan residues indicated that they were highly exposed to the aqueous solvent. Small angle X-ray scattering (SAXS) was used to access the overall structure and shape of scHsp101 in the presence and in the absence of nucleotides. These experiments revealed that scHsp101 undergoes large conformational changes upon nucleotide addition, as observed by changes in distance distribution function, maximum distance, and radii of gyration. These conformational changes were also investigated by analytical ultra centrifugation assays (AUC), allowing the confirmation that the adenosine nucleotides are involved in the formation of a hexamer. Both SAXS and AUC also demonstrate that high ionic strength influence negatively the oligomerization process, avoiding the formation of larger oligomers. The results herein described add to the yet poorly understood structure/activity relationship of ClpB/Hsp100 proteins, which will be discussed. Supported by FAPESP, CNPq/MCT, and LNLS.