Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (08): 1785-1792.doi: 10.3866/PKU.WHXB201305271

• BIOPHYSICAL CHEMISTRY • Previous Articles     Next Articles

Acid-Induced Unfolding Process of Myoglobin and Its Mutant under Macromolecular Crowding Conditions

ZHANG Yu-Jiao1, TANG Qian1, CAO Hong-Yu1, ZHENG Xue-Fang1,2   

  1. 1 School of Life Science and Biotechnology, Dalian University, Dalian 116622, Liaoning Province, P. R. China;
    2 Liaoning Key Lab of Bio-organic Chemistry Dalian University, Dalian 116622, Liaoning Province, P. R. China
  • Received:2013-03-18 Revised:2013-05-27 Published:2013-07-09
  • Contact: ZHENG Xue-Fang E-mail:dlxfzheng@126.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21271036, 20871024).

Abstract:

In this paper, we studied the unfolding process of myoglobin (Mb) and its mutant Mb(D60K) induced by acid under macromolecular crowding conditions, using ultraviolet-visible absorption, synchronous fluorescence, and circular dichroism (CD) spectroscopies. The spectroscopic data showed that, with the addition of Dextran70 or Ficoll70, the denaturation midpoint of Mb(WT) decreased from 4.25 to 3.78 or 3.76, respectively. In addition, the acid tolerance of Mb(WT) improved under macromolecular crowding conditions. The denaturation midpoint of Mb(D60K) was 4.19, which was a slight decrease from that of Mb (4.25). Upon addition of Dextran70 or Ficoll70, the denaturation midpoint of Mb(D60K) decreased from 4.19 to 3.74 or 3.12, respectively. The spectroscopic results illustrated that the amino acid mutant and crowding agents could stabilize the microenvironment surrounding the heme and aromatic amino acid as well as the second structure of Mb, protecting its native state.

Key words: Crowding agent, Acid denaturation, Myoglobin, Mutant, Spectrometry

MSC2000: 

  • O641