THE ROLE OF WATER IN STABILIZING THE NATURAL STRUCTURE OF MYOGLOBIN-A FOURIER TRANSFORM INFRARED SPECTROSCOPIC STUDY
水在稳定肌红蛋白天然结构中的作用

The effects of water on the secondary structure of myoglobin was investigated in the relative huminity (RH) range of 0 to 100% by means of Fourier transform infrared spectroscopy and curve-fitting. At dryness, the relative contents of a-helix, extended and disordered structures are about 61%, 22% and 17%, respectively. As the degree of hydration increases, the content of disordered structure decreases and those of ordered secondary sturcture increase. Such a structure transition is most significant at the RH lower than 44% and a complicated interchange of disordered to ordered structure takes place at 86 to 100%RH, Where the relative contents of the three substructures are 75%, 21% and 4%, respectively, the same as those in crystal and solution. The results confirm our previous conclusion that water acts as a plasticizer for the flexibility and a catalyst for mobility and conformation of peptide chains.