WHEAT KERNEL 0.19 ALPHA-AMYLASE INHIBITOR EXISTS AS A HOMODIMER IN SOLUTION. AN ASYMMETRIC UNIT CONTAINS TWO DIMERS. THREE NON-CRYSTALLOGRAPHIC TWO-FOLD AXES WHICH ARE PERPENDICULAR TO EACH OTHER RELATE THE FOUR MONOMERS. A: FIRST MOLECULE IN AN ASYMMETRIC UNIT. IT FORMS A BIOLOGICAL DIMER WITH CHAIN B. B: SECOND MOLECULE IN AN ASYMMETRIC UNIT. IT FORMS A BIOLOGICAL DIMER WITH CHAIN A. C: THIRD MOLECULE IN AN ASYMMETRIC UNIT. IT FORMS A BIOLOGICAL DIMER WITH CHAIN D. D: FOURTH MOLECULE IN AN ASYMMETRIC UNIT. IT FORMS A BIOLOGICAL DIMER WITH CHAIN C.