Shibayama N, Saigo S
Department of Physics, Jichi Medical School, Tochigi, Japan.
J Mol Biol. 1995 Aug 11;251(2):203-9. doi: 10.1006/jmbi.1995.0427.
We have used the sol-gel method to encapsulate oxy- and deoxy haemoglobins in transparent wet porous silica gels and fixed their original functional states with the retention of the reversible oxygenation properties as well as the intact spectroscopic properties. Haemoglobin originally encapsulated in aerobic gel binds oxygen non-cooperatively with very high affinity, corresponding to that for the last oxygen molecule binding to haemoglobin in solution. In contrast, haemoglobin originally encapsulated in anaerobic gel binds oxygen non-cooperatively with very low affinity, comparable to that for the first oxygen molecule binding to haemoglobin in solution. Furthermore, a detailed comparison of visible absorption spectra of deoxygenated haemoglobins originally encapsulated in aerobic and anaerobic gels indicates the retention of their original quaternary structures during the oxygenation or deoxygenation process. These results demonstrate that oxygen affinities of oxy- and deoxyhaemoglobins in solution can be satisfactorily fixed by encapsulation in wet porous silica gels, which presumably prevents the changes in the quaternary structures of haemoglobin. In addition, these results suggest a new capability of the sol-gel method to control the structural states of a variety of proteins, and further open up a new area of investigation of protein structure-function relationships.
我们采用溶胶-凝胶法将氧合血红蛋白和脱氧血红蛋白封装在透明的湿多孔硅胶中，并固定它们的原始功能状态，使其保留可逆的氧合特性以及完整的光谱特性。最初封装在有氧凝胶中的血红蛋白以非常高的亲和力非协同结合氧气，这与溶液中最后一个氧分子与血红蛋白结合时的亲和力相当。相比之下，最初封装在厌氧凝胶中的血红蛋白以非常低的亲和力非协同结合氧气，这与溶液中第一个氧分子与血红蛋白结合时的亲和力相当。此外，对最初封装在有氧和厌氧凝胶中的脱氧血红蛋白的可见吸收光谱进行详细比较表明，在氧合或脱氧过程中它们保留了原始的四级结构。这些结果表明，通过封装在湿多孔硅胶中可以令人满意地固定溶液中氧合血红蛋白和脱氧血红蛋白的氧亲和力，这大概可以防止血红蛋白四级结构的变化。此外，这些结果表明溶胶-凝胶法具有控制多种蛋白质结构状态的新能力，并进一步开辟了蛋白质结构-功能关系研究的新领域。
