蛋白質分子間的相互作用力為使蛋白質溶液中呈現多樣化聚集現象的主因，而相互作用力的大小會受到溶液環境條件的影響。因此，本研究我們固定鹽類溶液為3wt% NaCl，緩衝溶液為0.1M NaAc，pH 4.5的條件下建立一球形蛋白質溶液相圖。利用加裝linkam控溫裝置和CCD的光學顯微鏡，紀錄觀察結晶溶解情形，得到溶解度數據。利用雲點測量儀偵測透光強度隨溫度的變化，測得雲點數據。然後，將兩個實驗數據分別帶入理論式子擬合，而得到液-固相界線和液-液相界線。蛋白質溶液便可依據濃度和溫度的不同，劃分成三個區域:透明均一區、液-固共存區、液-液分離區。

添加不同種鹽類實驗中，我們固定蛋白質濃度為85 mg/ml，緩衝溶液為0.1M NaAc，pH 4.5，選用四種鹽類 (NaCl, NaBr, NaI, NaClO4) 測定雲點溫度隨鹽類濃度的變化。由實驗結果得知，雲點溫度呈現的行為相當複雜。在低濃度鹽類區，陰離子對雲點溫度的影響性會遵循inverse Hofmeister series；在較高濃度鹽類區，順序會反轉成direct Hofmeister series。我們試著以chaotropic陰離子特定吸附現象和由離子改變表面張力大小的行為去解釋雲點溫度呈現的複雜行為。

The interaction between protein molecules is the main reason for the diversified aggregation phenomenon in protein solution, and the interaction force is affected by the environmental conditions of the solution. Therefore, in this study, we established a phase diagram for spherical protein solution, which fixed a salt solution of 3wt% NaCl and a buffer solution of 0.1M NaAc at pH 4.5. Optical microscope equipped with linkam temperature control device and the CCD was used to record and observe the dissolution of the crystal to obtain the solubility data. The cloud point data was measured by detecting the change of the light transmission intensity with temperature by using a cloud point measuring device. Then, the two experimental data were respectively fitting into the theoretical equation to obtain liquid-solid phase boundary and the liquid-liquid phase boundary. According to different concentration and temperature, the protein solution can be divided into three regions: homogeneous region, liquid-solid coexistence region and liquid-liquid separation region.

In the experiment of adding different kind of salts, we fixed the protein concentration of 85 mg/ml and a buffer solution of 0.1M NaAc at pH 4.5. Four kind of salts (NaCl, NaBr, NaI, NaClO4) were used to determine the change of cloud point temperature with salt concentration. It’s known from the result of the experiment that the behavior of cloud point temperature is quite complicated. In low salt concentration region, the effect of anions on cloud point temperature follows an inverse Hofmeister series. At higher salt concentration region, the order reverts to a direct Hofmeister series. We tried to explain the complex behavior of cloud point temperature by the specific adsorption phenomenon of chaotropic anions and the behavior of changing the surface tension by ions.

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