物理化学学报 >> 2007, Vol. 23 >> Issue (07): 1025-1031.doi: 10.3866/PKU.WHXB20070712

研究论文 上一篇    下一篇

DMSO对鸡蛋白溶菌酶溶液变性的影响

方盈盈; 胡新根; 于丽; 李文兵; 朱玉青; 余生   

  1. 温州大学化学与材料科学学院, 浙江 温州 325027; 山东大学胶体与界面化学教育部重点实验室, 济南 250100
  • 收稿日期:2006-12-21 修回日期:2006-03-09 发布日期:2007-07-03
  • 通讯作者: 胡新根 E-mail:hxgwzu@126.com

Effect of DMSO on Denaturation of Hen Egg-white Lysozyme in Aqueous Solution

FANG Ying-Ying; HU Xin-Gen; YU Li; LI Wen-Bing; ZHU Yu-Qing; YU Sheng   

  1. College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, Zhejiang Province, P. R. China; Key Laboratory for Colloid and Interface Chemistry of the Ministry of Education, Shandong University, Jinan 250100, P. R. China
  • Received:2006-12-21 Revised:2006-03-09 Published:2007-07-03
  • Contact: HU Xin-Gen E-mail:hxgwzu@126.com

摘要: 利用差示扫描量热(DSC)和温度调制差示扫描量热(MDSC)研究了鸡蛋白溶菌酶在纯水及二甲基亚砜(DMSO)/水混合溶剂中的热变性过程, 探讨了酶的浓度、扫描速率和共溶剂的含量对热变性行为的影响规律. 在纯水溶液中, 溶菌酶的变性焓(△Hm)随酶浓度的增大而增大. 而在DMSO/水混合溶剂中, 变性温度(Tm)随DMSO体积分数的增大向低温方向移动, 变性峰变低变宽; 当DMSO体积分数达到70%后, 热变性曲线变成了一条光滑的直线. 另外, 在纯水溶液中溶菌酶的MDSC图除了出现DSC中可观察到的主吸热峰(I)外, 在峰(I)的前面还出现一个小而对称的吸热峰(II), 并且当体系中有DMSO存在时也未能观察到此峰. 当溶菌酶浓度增大时, Tm(II)移向低温, △Hm(II)减小, Tm(I)与Tm(II)之间的距离变长. 吸热峰(II)的出现被认为是由于水溶液中溶菌酶二聚体的可逆离解造成的.

关键词: DSC, MDSC, DMSO, 鸡蛋白溶菌酶, 热变性

Abstract:

A study on thermal denaturation of hen egg-white lysozyme (HEWL) was carried out by differential scanning calorimetry (DSC) and modulated temperature differential scanning calorimetry (MDSC). It was found that DSCprofiles ofHEWLwere dependent on heating rates and concentrations of enzyme as well as cosolvent. The enthalpy of denaturation (△Hm) increasedwith increasing enzyme concentration in aqueous solution. In aqueous solution containing dimethylsolfoxide (DMSO), denaturation temperature (Tm) shifted toward lower temperature, and the transition peak became shallower and broader with increasing volume proportion of DMSO. When the content of DMSO was more than 70%, only a declining smooth line could be observed instead of a single endothermic transition curve. Interestingly, fromMDSC curves of HEWL in aqueous solution without DMSO, a small and symmetrical peak in front of the main transition (I) was observed marginally, which was regarded as a pre-transition (II). Specially, this small and marginal peak could not be found in aqueous solution containing DMSO. In addition, with increasing amount of protein, Tm(II) shifted toward lower temperature, and △Hm(II) decreased along with the temperature gap between two transitions lengthened. The results were considered to be due to the reversible dissociation of HEWL dimers in aqueous solution.

Key words: DSC, MDSC, DMSO, Hen egg-white lysozyme, Thermal denaturation

MSC2000: 

  • O642