Structural properties of Brazil nut 11S globulin, excelsin.

The structural properties of Brazil nut 11S globulin, excelsin, were examined by polyacrylamide gel electrophoresis, circular dichroism, electron microscopy and X-ray diffraction. Excelsin was separated into five fractions by SDS-gel electrophoresis, and the molecular weight of the largest subunit was 51, 000. The contents of helical, β-form and unordered structure were 14, 27 and 59%, respectively. The molecular shape was a double-layer polygon with a hole at the centre, and the molecular dimensions were 72×69×62Å. The space group of the crystal was R3.