The Partial Influence Of Berberine On Three Important Digestive Enzymes

Berberine is a kind of isoquinoline alkaloid which is extracted from the roots and barks of ranunculacenep plant coptis (coptis chinesis Feranch), berberine is the major component in coptis with a wide range of pharmacological effect. As a drug , berberine mainly play function in the gastrointestin. Therefore, berberine will inevitably interact with animals' and the body's digestive enzymes.We studied the partial influence of berberine on pepsin, trypsin and a-amylase.It was found that berberine could inhibit the activity of three digestive enzymes. The inhibiting ratio of berberine on trypsin was highest, whereas that of a-amylase was lowest.When the concentration ratio of berberine to enzymes was 1.5/1, the inhibiting ratios of berberine on those three enzymes were 16.63%,10.05% and 8.29%.When adding different concentrations of berberine into those three enzymes,the UV absorption of pepsin near 275nm, the UV absorption of trypsin near 270nm and the UV absorption of a-amylase near 265nm increased according to the rising concentration of berberine.When adding different concentrations of berberine into those three enzymes, it led to the fluorescence quenching of the three enzymes. The Stern-Volmer plots at different temperature showed that the quenching mechanism of berberine to the three enzymes was probably a static quenching process,the dynamic quenching constant K_SV of those,three enzymes decreased as temperature increased from 20℃to 37℃, As the average fluorescence life of macromolecule was about 10^-8 s, the dynamic quenching rate constants Kq of berberine on those three enzymes decreased as temperature increased from 20?? to 37??,The dynamic quenching rate constants Kq were far greater than all the greatest proliferating and collising constant of biological macromolecules, so the fluorescence quenching of berberine on the three enzymes was not caused by molecular diffusion and collision . Berberine mightbe "embedded" among the enzyme molecule,and conformed a certain structure of complex,the complex caused the static quenching. The figure of lg[(F₀-F) /F]-lg[Q] showed that when temperature was 20??, the binding sites of pepsin, trypsin and a-amylase were 1.12,1.30,1.17, while at 37?? was 1.09,1.29,1.16, which showed there was only one binding site. As the temperature rised, the binding constant K_A of berberine on pepsin, trypsin and a-amylase decreased, which also showed that the quenching mechanism was static quenching.The thermodynamic equation showed that,when the temperature were at both 20?? and 37??, the thermodynamic parameters |¤H>0, |¤G<0, |¤S>0. From the Ross' conclusion: |¤H and |¤S were both greater than 0, the interaction force was a typical hydrophobic interaction. Therefore, interaction force of berberine on the three enzymes was hydrophobic interaction.