Protein Bodies from Buckwheat Seed Cotyledons: Isolation and Characteristics

Protein bodies were isolated from cotyledons of dry buckwheat seeds by homogenization in acetone with subsequent purification in a 1.26 g cm−3 to 1.53 g cm−3 linear density gradient of a mixture of acetone with CCI4. The purified fraction of protein bodies with globoids (PB I) had a buoyant density of 1.48–1.51 g cm−3 and was intact according to microscopic data. Localization of hydrolytic enzymes and proteinase inhibitors in the PB I fraction and in the fraction of the cytoplasm and membrane material (CMM) was studied. It was shown that acid hydrolytic enzymes, such as aspartic proteinase, carboxypeptidase, acid phosphatase, α-D-mannosidase and N-acetyl-β-glucosaminidase, as well as chymotrypsin and trypsin inhibitors were predominantly localized in the PB I. BAPAase and SH-activated caseinase activities were equally distributed between the PB I and CMM fraction. The activities of leucine aminopeptidase and SH-independent caseinase were noticeably predominant in the CMM fraction.