Abstract: The ternaty complex formation constants of 7-oxabicyclo-[2,2, 1]-hept-5-ene-2,3-dicar-boxylic acid (OHDA) with several typical amino acids and Zn(Ⅱ), Cu(Ⅱ) were potentiometrically determined under physiological conditions(37℃, 0. 15 mol/L NaCl). The calculation of mixed ligand complex constants of OHDA shows that the OHDA and amino acids both share the great benefit from the formation of the mixed complexes. Computer simulation of blood plasma model indicates that OHDA acting as a drug ligand does participate in the complicate biological equilibrium of low molecular weight metal complexes disturbing the distribution of essential metal ions--zinc which propably results in changing the activity and function of crucial zinc--containing enzymes. Meanwhile, attention must be paid to the effect of administering OHDAon Cu(Ⅱ) ion balance.

Key words: 7-Oxabicyclo-[2,2,1]-hept-5-ene-2,3-dicarboxylic acid, Ternary complex, Computer simulation