| With the development of science and technology, a large amount of chemical substances are produced and used, which promote the development of industry and agriculture. Among these substances, there are organic dyes, chemical materials, pesticides, which are poisonous and are harmful to people and animals. Since 1950s, especially, a great lot of pesticides and herbicides were used in agriculture to improve food production. The residues in environment could enter into the body by means of ingestion, inhalation or skin contact, and interact with biomacromolecules such as protein, enzyme and nucleic acid directly or indirectly and then affect their function or genetic characteristic. Considering physiological importance of serum albumin and DNA, we investigated the interactions of chiral herbicides dichlorprop(DCPP) with bovine and human serum albumin and metolachlor with calf thymus DNA by spectroscopic and other methods respectively, so as to make clear of the interaction mechanism.In the first part of this paper, binding constants were determined by remarkable static quenching effect of enantiomers of DCPP to the intrinsic fluorescence of BSA and HSA. Great binding constant values suggest that DCPPs have high affinity to BSA and HSA. And we found that high temperature helps the binding between DCPPs and serum albumins. As to BSA, the affinity order is as follows: S-DCPP > Rac-DCPP > R-DCPP; and to HSA, the affinity order is as follows: R-DCPP > Rac-DCPP > S-DCPP.The studies of synchronous fluorescence method and the analyses of structure and function of BSA and HSA show that DCPPs bind to sub domainⅡA of BSA and HSA where Trp 214 are located, and form 1:1 complexes. Thermodynamics research shows that the hydrophobic contact plays an important role in the interaction, but there may also be other forces, such as electrostatic attraction, van der Waals interaction and hydrogen bonds.In the second part, the interaction between enantiomers of metolachlor and calf thymus DNA was studied. The results suggest that metolachlors could bind to ctDNA forming adducts. Because metolachlor is a chiral molecular, different enantiomers have different binding constants to ctDNA. S-metolachlor's binding constant to ctDNA is bigger than Rac-metolachlor's under the same temperature, which is to say, the S-isomer's conformation is more propitious to combined with ctDNA. At 25℃, the binding constants of Rac-metolachlor and S-metolachlor with ctDNA are 3.51×10~3 L/mol and 3.81×10~3 L/mol, respectively. Seeing about the interaction between metolachlor and ctDNA varying ion intensity, and investigating the effect of metolachlor on the melting temperature and viscosity of ctDNA, we conclude that metolachlor could interact with ctDNA through groove binding. |
