The effects of enzymatic modification(EM) treatment on structural characteristics of highly denatured defatted commercial soy flakes(HDDSF) were investigated in order to analyze the relationship between its solubility and structure.Protein solubility,surface hydrophobicity(Ho),surface sulfhydryl(SSH) content,free sulfhydryl(FSH) content,total sulfhydryl(TSH) content and disulfide bond(-S-S-) content were evaluated.Protein subunits profiles for the hydrolysate were altered by the EM treatment and major changes were observed for the hydrolysate.With DH increasing,the solubility of HDDSF was increased significantly.The SSH content,FSH content and the TSH content were showed different changes,above all the-S-S-content of HDDSF was significantly increased after EM treatment at DH1 %,but was gradually decreased with further increase in DH.Analysis showed that the soluble aggregates were formed during EM treatment.Covalent interactions(i.e.disulfide bonds) was involved in the formation of soluble aggregates.The formation of soluble aggregates significantly improved the solubility of HDDSF,and the soluble aggregates were hydrolyzed by Alaclase thereafter.