Hawkes J J, Pethig R
Institute of Molecular and Biomolecular Electronics, University College of North Wales, Bangor, U.K.
Biochim Biophys Acta. 1988 Jan 4;952(1):27-36. doi: 10.1016/0167-4838(88)90098-2.
Dielectric measurements have been made on lysozyme-compressed powders as a function of hydration and of the pH at which the samples were lyophilised. A dielectric dispersion previously described in the literature and known as the alpha-dispersion is found to be strongly influenced by the lyophilisation pH, and reaches a maximum magnitude at around pH 11. A dielectric loss of the form of the alpha-dispersion is observed in polylysine hydrobromide and the sodium salt of polyglutamic acid, but not for polyglycine. These results can be understood in terms of proton transfer between the ionisable side-groups, as well as by the controlling influence of counter-ions in moderating the energetics of the proton transfer processes. Another, weaker and hitherto unreported, dielectric loss process has been found for lysozyme, polyglycine, polylysine and poly(glutamic acid). This is referred to as the alpha 2-dispersion and its characteristics can be understood in terms of vibrational motions of the polypeptide backbones and the plasticising action of bound water.
已对溶菌酶压缩粉末进行了介电测量，测量结果是水合作用以及样品冻干时的pH值的函数。文献中先前描述的一种介电色散，即所谓的α色散，被发现受到冻干pH值的强烈影响，并在pH值约为11时达到最大幅度。在聚赖氨酸氢溴酸盐和聚谷氨酸钠盐中观察到了α色散形式的介电损耗，但在聚甘氨酸中未观察到。这些结果可以通过可电离侧链基团之间的质子转移来理解，也可以通过抗衡离子对质子转移过程能量学的控制影响来理解。对于溶菌酶、聚甘氨酸、聚赖氨酸和聚（谷氨酸），还发现了另一种较弱且迄今未报道的介电损耗过程。这被称为α2色散，其特性可以通过多肽主链的振动运动以及结合水的增塑作用来理解。
