Using electron absorption spectra and CD( circular dichroism) spectra, we studied the interaction between the assembly of chiral acid modified porphyrinatozinc (Ⅱ)( Thr--TPPZn ) and DNA. The helical assembly of Thr---TPPZn can bind to DNA. The amino acid residue of the assembly of L-----Thr ---TPPZn forms hydrogen bonds with the ohosphate chain of DNA, and the binding belongs to external type. As to the assembly of D----Thr ----TPPZN, the porphyrin unit formsπ-π stacking with the base pair of DNA besides the above mentioned hydrogen bonding. In this case, the binding is a partial intercalation. The reason for the different binding mode is that the assembly of L amino acid modified porphyrinatozinc ( Ⅱ) is left -- handed helical, which cannot match the right --handed helical of DNA, while the assembly of D--amino acid modified porphrinatozinc (Ⅱ) is right --handed helical that can match the helical of DNA.

Key words: PORPHYRIN, AGGREGALES, DEOXYRIBONUCLEIC ACID, INTERACTIONS