The relationship between the limited proteolysis and conformation of native glycinin was studied by the following methods: analyses of the proteolytic digestion of chemically modified glycinin, circular dichroism (CD) measurements, a secondary structure prediction from the amino acid sequence and a hydropathy index analysis. The locations of tryptic fragments of glycinin were confirmed from the N-terminal amino acid sequences of the fragments. T fragments and P fragments were located at the N-terminal and central area of the acidic polypeptide chains, respectively. One of the cleavage sites was the Arg residue of around the 100th from the N-terminal side. The regions digested by limited trypsinolysis were presumed to be flexible, hydrophilic and near the surface of the molecule by prediction methods from the amino acid sequence. The other regions were predicted to be compact and beta-sheet in nature, almost 40-50% of the amino acid residues being predicted as beta-sheet from the amino acid sequence and from CD data.