Kitajima N, Tsukashima S, Fujii D, Tachibana M, Koizumi H, Wako K, Kojima K
Citizen Holdings Company, Ltd, 840, Shimotomi, Tokorozawa, Saitama 359-8511, Japan.
Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Jan;89(1):012714. doi: 10.1103/PhysRevE.89.012714. Epub 2014 Jan 21.
The ultrasonic sound velocities of cross-linked orthorhombic hen egg-white lysozyme (HEWL) crystals, including a large amount of water in the crystal, were measured using an ultrasonic pulse-echo method. As a result, seven elastic constants of orthorhombic crystals were observed to be C11 = 5.24 GPa, C22 = 4.87 GPa, C12 = 4.02 GPa, C33 = 5.23 GPa, C44 = 0.30 GPa, C55 = 0.40 GPa, and C66 = 0.43 GPa, respectively. However, C13 and C23 could not be observed because the suitable crystal planes could not be cut from bulk crystals. We conclude that the observed elastic constants of the cross-linked crystals are coincident with those of the intrinsic crystals without cross-linking. Moreover, the characteristics of the elastic constants in orthorhombic HEWL crystals are due to the fact that the shear elastic constants, C44, C55, and C66, are softer than in tetragonal crystals. That is, the shear components, C44, C55, and C66, are one half of those of the tetragonal crystals.
采用超声脉冲回波法测量了交联正交晶系鸡蛋白溶菌酶（HEWL）晶体的超声声速，该晶体在晶体内含有大量水分。结果表明，正交晶系晶体的七个弹性常数分别为C11 = 5.24 GPa、C22 = 4.87 GPa、C12 = 4.02 GPa、C33 = 5.23 GPa、C44 = 0.30 GPa、C55 = 0.40 GPa和C66 = 0.43 GPa。然而，由于无法从块状晶体上切割出合适的晶面，所以未能观测到C13和C23。我们得出结论，所观测到的交联晶体的弹性常数与未交联的本征晶体的弹性常数一致。此外，正交晶系HEWL晶体弹性常数的特点是，其剪切弹性常数C44、C55和C66比四方晶系晶体中的更软。也就是说，剪切分量C44、C55和C66是四方晶系晶体中相应分量的一半。
