Ogunmola G B, Zipp A, Chen F, Kauzmann W
Proc Natl Acad Sci U S A. 1977 Jan;74(1):1-4. doi: 10.1073/pnas.74.1.1.
The spectra of the ferric form of most heme proteins [metmyoglobin, methemoglobin, horse radish peroxidase (EC 1.11.1.7), and ferricytochrome c at pH 1.5] are converted from high-spin (open crevice) structure to low-spin (closed crevice) form under pressure. Pressures up to 8000 kg/cm2 (780 MPa) have no effect on the spectra of high-spin ferro- and ferricytochrome c, which have a closed crevice structure at pH 7.0. Spectra of deoxy-ferromyoglobin and deoxy-ferrohemoglobin are reduced in intensity, but pressure does not change the positions of the absorption maxima. Cyanide ion prevents pressure-induced spectral changes in metmyoglobin and methemoglobin up to 8000 kg/cm2. Carbon monoxide (with a high affinity for the ferro heme iron) has a similar effect on ferromyoglobin and ferrohemoglobin. The pressure required to cause spectral changes in the heme proteins falls in the order, cytochrome c (pH 7.0) greater than horse radish peroxidase greater than myoglobin greater than hemoglobin. We have calculated a volume change of --50 cm3/mol associated with the configurational change accompanying the reformation of the iron-methionine bond in cytochrome c at low pH.
大多数血红素蛋白的高铁形式（肌红蛋白、血红蛋白、辣根过氧化物酶（EC 1.11.1.7）以及pH值为1.5时的高铁细胞色素c）在压力作用下，其光谱会从高自旋（开放裂隙）结构转变为低自旋（闭合裂隙）形式。高达8000 kg/cm²（780 MPa）的压力对高自旋亚铁细胞色素c和高铁细胞色素c的光谱没有影响，它们在pH值为7.0时具有闭合裂隙结构。脱氧肌红蛋白和脱氧血红蛋白的光谱强度降低，但压力不会改变吸收最大值的位置。氰离子可防止高达8000 kg/cm²压力下肌红蛋白和血红蛋白的压力诱导光谱变化。一氧化碳（与亚铁血红素铁具有高亲和力）对肌红蛋白和血红蛋白有类似影响。导致血红素蛋白光谱变化所需的压力顺序为：细胞色素c（pH值为7.0）＞辣根过氧化物酶＞肌红蛋白＞血红蛋白。我们计算出，在低pH值下，细胞色素c中伴随铁 - 甲硫氨酸键重新形成的构型变化相关的体积变化为 - 50 cm³/mol。
