带正电荷蛋白在纳米/微米草酸钙晶体上的吸附特性及其与带负电荷蛋白吸附的比较
Adsorption Properties of Cationic Protein on Nano/Micron Calcium Oxalate Crystals and a Comparison with Anionic Protein Adsorption
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温小玲 暨南大学生物矿化与结石病防治研究所, 暨南大学化学系, 广州 510632  
孙新园 暨南大学生物矿化与结石病防治研究所, 暨南大学化学系, 广州 510632  
欧阳健明 暨南大学生物矿化与结石病防治研究所, 暨南大学化学系, 广州 510632 toyjm@jnu.edu.cn 
摘要: 研究尺寸分别为100 nm和3 μm的一水草酸钙(COM)和二水草酸钙(COD)晶体对带正电荷的蛋白溶菌酶(LSZ)的吸附差异,并与带负电荷的蛋白牛血清白蛋白(BSA)的吸附进行了比较。LSZ在纳米/微米COM和COD晶体上的吸附都很好的拟合了Langmuir模型,属于单分子层吸附。纳米/微米COM和COD对LSZ的最大吸附量顺序为COD-100 nm >COM-100 nm >COD-3 μm >COM-3 μm;晶体的比表面积越大,曲率越小,晶体表面所带电荷越负,晶体结晶水越多,均导致LSZ吸附量越大。体系离子强度和pH值亦影响LSZ的吸附。随着NaCl浓度增加,LSZ的吸附量减小,说明Na+离子能与带正电荷的蛋白LSZ竞争晶体表面的吸附位点,导致晶体表面吸附LSZ的位点减少。晶体对LSZ的最大吸附量都出现在LSZ的等电点附近(pH=10.7);在pH=5~8(生理条件)时,LSZ的吸附量随pH值的增大而增大。本文结果提示,通过减小尿液的pH值或者适当增大尿液的离子强度,可以减小LSZ在尿微晶上的吸附量,有可能达到抑制草酸钙结石的效果。
关键词: 草酸钙  带正电荷的蛋白  溶菌酶  竞争吸附  离子强度  pH值
基金项目: 国家自然科学基金(No.21371077)资助项目。
Abstract: The adsorption difference of cationic protein lysozyme (LSZ) on calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) crystals with a size of 100 nm and 3 μm, respectively, were investigated and compared with that of anionic protein bovine serum albumin (BSA). All of the adsorption isotherms were fitted better with Langmuir model, indicating a monolayer adsorption of LSZ on nano/micron COD and COM surface. The maximum adsorption quality of LSZ follows the order:COD-100 nm >COM-100 nm >COD-3 μm >COM-3 μm. That is, the greater the specific surface area is, the smaller the crystal curvature would be, so the greater of LSZ adsorption amount was generated; and the more negative charges and the more crystal water on crystal surface also result in the greater of LSZ adsorption. The ionic strength and pH value of system can also affect LSZ adsorption. With the concentration of NaCl increases, the adsorption quantity of LSZ reduced, it indicated that Na+ ions and cationic LSZ form a competitive adsorption, which reducing the adsorption sites of LSZ. The maximum adsorption of LSZ appears at the isoelectric point of LSZ (pH=10.7). In pH=5~8 (physical condition), LSZ adsorption quantity increases with the increase of pH value. The results suggest that the adsorption quality of LSZ on nano/micron COM and COD crystals can be reduced by reducing the pH value or increasing the ionic strength of urine appropriately, and thus the formation of CaOx urinary stones maybe inhibited.
Keywords: calcium oxalate  cationic protein  lysozyme  competitive adsorption  ionic strength  pH value
投稿时间:2016-05-14 修订日期:2016-11-11
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