Study On The Interaction Of Chlorine Disinfection Byproducts-Chloroform In Drinking Water With Catalase

In this thesis, the effect of chloroform on catalase, tyrosine and tryptophan had been determined by using fluorescent spectrometry. In the mean time ,the influence of pH, metal ions presence on the combination of them had also been determined.The results showed that the fluorescence of catalase can be quenched gradually with increasing of chloroform concentration in the chloroform-catalase binary system. The reason probably is that catalase has combinated with chloroform and formed ground complexes, and as a result causes the change of catalase conformation. Copper ion and iron ion can also cause the fluorescence quenching of catalase, but the combination intensity of catalase with metal ions are stronger than that of catalase with chloroform, showed by the combination constant is 32 times for catalase with copper ion and 141 times for catalase with iron respectively to that of catalase with chloroform. Chloroform and metal ions both effect mainly on the protein part of catalase, but have no influence on the fluorescence of prosthetic group in the enzymy.There are different influences of metal ions on the effect of chloroform with catalase. Copper ion can influence the combination of catalase with chloroform. The combination intensity of catalase with chloroform decreased with the increasing of copper ion concentration. The possible mechanism is that copper ion can alter the combination position of chloroform on the surface of catalse. Iron ion has no influence on the effect of chloroform with catalase. The combination intensity of catalase with chloroform keeps stability with the increasing of iron ion concentration in the system.The effect of chloroform with catalase can be affected by pH. On the condition of pH7.2, the combination of catalase with chloroform was the strongest. But on the condition of acidity and alkalescence, the combination intensity is decreased.In order to further study the effect of chloroform with catalase, the activity of catalase had been determined. The results showed lowconcentration of chloroform can activate catalase, but high concentration of it can inhibit catalase. The influence of chloroform to catalase activity shows a nonlinear variation, but that to catalase fluroesence shows a linear variation. This shows chloroform not only can alter the conformation of catalase, but also can effect the catalysis group or haptophoric group by other mechnisms.The results of fluorescence analysis showed that fluorescence of tyrosine and tryptophan can be quenched by chloroform, Copper ion and iron ion respectively. But the combination constant of tyrosine and tryptophan with the metal ions is much higher than that of tyrosine and tryptophan with chloroform. The metal ions have no influence on the effect of chloroform with tyrosine and tryptophan.