Methods of preparing plant-derived proteins or suprastructure proteins, are provided. The method may comprise obtaining a plant, or plant matter comprising apoplast-localized proteins, or suprastructure proteins, producing a protoplast/spheroplast fraction and apoplast fraction from the plant or plant matter, and recovering the apoplast fraction. The apoplast fraction comprises plant-derived proteins or suprastructure proteins. Alternatively, the proteins, or suprastructure proteins, may be obtained from plant or plant matter comprising plant-derived proteins or suprastructure proteins, by digesting the plant matter using a cell wall degrading enzyme composition to produced a digested fraction. The digested fraction is filtered to produced a filtered fraction, and the plant-derived proteins or suprastructure proteins, are recovered from the filtered fraction.
