利用紫外線光譜、圓二色光譜、螢光光譜來探討在不同濃度鋅離子、不同pH值環境下，對胰蛋白酶(trypsin)之活性及結構的影響。實驗的結果顯示出：當有鋅離子存在時，會對胰蛋白酶形成抑制作用(非競爭性的)。在[Zn2+]=166mM，pH 7.16下，相對於不加鋅離子，活性下降最大可達33.57％；在[Zn2+]=166mM，pH值(由7.16 → 6.5)下時也會使得胰蛋白酶的活性下降，相對於不加鋅離子，活性下降最大可達42.92％。在Far-UV CD的圖譜中發現，在有鋅離子存在的胰蛋白酶溶液，其二級結構會有明顯的變化，隨[Zn2+]增加α-helix成份比例明顯增加；改變pH值時也會造成類似的結果。在Near-UV CD的圖譜中發現，當加入鋅離子或是改變pH值時，對於三級結構並沒有造成明顯的變化，只有在光譜的強度方面發生些微的改變，而這也代表著胰蛋白酶的局部的構形發生變化。在螢光光譜中發現，ANS、Trp、MIANS螢光光譜在加入鋅離子時都會造成胰蛋白酶表面疏水性區域增加，當使pH值下降時，我們也發現胰蛋白酶表面疏水性區域增加的幅度隨pH值下降而下降。因此，綜合上述光譜的結果，發現當加入不同濃度鋅離子及改變pH值都會造成胰蛋白酶活性和結構上的改變。

　　Circular Dichroism (CD) and fluorescence Spectroscopy have been used to investigate the effects of pH value and Zn2+ concentration on the bioactivity and structure of trypsin. It was found that the existence of the Zn2+ is capable of affecting the hydrolytic ability of trypsin on the substrate of N-benzoyl arginine ethyl ester (BAEE). The inhibition of Zn2+ on trypsin is uncompetitive binding at a site different from that of BAEE. When [Zn2+] = 166 mM and at pH 7.16, the initial hydrolytic rate toward BAEE was dropped 33.57%; furthermore, with the same concentration of Zn2+and pH 6.5, it was found that 42.92% of the activity was lost. In order to investigate the structural change of trypsin under this condition, CD and Fluorescence spectra were measured. Far-UV CD spectra showed that the existence of Zn2+ caused the percentage of 2o structural component of α-helix increased with the increasing of Zn2+ concentration. And the deviation of pH from 8 also resulted in the same results. However, the Near-UV CD spectra indicated the tertiary structure of trypsin did not show obvious changes, except little decreasing of intensity, suggesting the structural changes caused due to the binding of Zn2+ was a local alteration. ANS, Trptophan and MIANS fluorescence spectra showed that the hydrophobic region increased with the existence of Zn2+, indicative of more tryptophan resides and aromatic side chain containing amino acid residues exposed; however, when pH value was in acidic condition, the hydrophobic region was decreased, suggesting low pH value is not a good condition for trypsin hydrolytic activity.

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