Uversky V N, Ptitsyn O B
Institute of Protein Research Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
J Mol Biol. 1996 Jan 12;255(1):215-28. doi: 10.1006/jmbi.1996.0018.
Equilibrium guanidinium chloride-induced unfolding of bovine carbonic anhydrase NB has been investigated by a combination of optical methods with size-exclusion chromatography. It has been shown that, as in the case of staphylococcal beta-lactamase, bovine carbonic anhydrase B unfolds at low temperature through two equilibrium intermediates; the molten globule and the pre-molten globule states. This pre-molten globule state has a hydrodynamic volume no more than twofold larger than that of the native state, i.e. is relatively compact. It has a pronounced far UV CD spectrum, suggesting the presence of a substantial secondary structure. It binds 8-anilinonaphthalene-1-sulphonate (though weaker than the molten globule state), which suggests the formation of solvent-exposed clusters of non-polar groups. Thus, this novel state of protein molecules shares a number of properties with the "burst" kinetic intermediate of protein folding and can be considered as its equilibrium counterpart.
通过光学方法与尺寸排阻色谱相结合，研究了平衡氯化胍诱导的牛碳酸酐酶NB的去折叠过程。结果表明，与葡萄球菌β-内酰胺酶的情况一样，牛碳酸酐酶B在低温下通过两个平衡中间体展开；即熔球态和预熔球态。这种预熔球态的流体力学体积比天然态大不超过两倍，即相对紧凑。它具有明显的远紫外圆二色光谱，表明存在大量二级结构。它能结合8-苯胺基萘-1-磺酸盐（尽管比熔球态弱），这表明形成了暴露于溶剂的非极性基团簇。因此，这种蛋白质分子的新状态与蛋白质折叠的“爆发”动力学中间体具有许多共同特性，可被视为其平衡对应物。
