Interactions of Aflatoxin with Histones and DNA ' Homer

Suimmtl7iarv. The interactions of aflatoxin B, with certain histone fractions and DNA were investigated by means of viscosity measurements and equiilibriuim dialysis. Two main histone fraction,s (F2b and Fl), both lysine-rich, were examined after treatment with the toxin. Fraction 2b and 1 differ in amino acid composition an(l behave differently, in regard to gross conformation, in the presence of electrolytes. Aflatoxin increased the viscosity of fraction 2b bu-t affected the viscosity of fraction 1 only slightly. Equtilibriuim d-ialysis experiments shoowed that aflatoxin was bound to both histone fractions. Aflatoxin also increased the viscosity of DNA and equilibrium dialysis showed that 1 molecule of the toxin -,vas boulnd to approximately every 5 nlucleotides of the nucleic acid. Binding constants for the aflatoxin complexes were calclulated as 1000 for F2b, 700 for Fl, and 5500 for DNA-. The biological implications of these data, in regard to the effect aflatoxin has on the information-transcription process, are discuissedl.