Low P S, Somero G N
Proc Natl Acad Sci U S A. 1975 Aug;72(8):3014-8. doi: 10.1073/pnas.72.8.3014.
Changes in enzyme conformation are often accompanied by large changes in volume. Model compound studies suggest that these volume changes may derive from two sources: (i) "hydration density" effects due to changes in the exposure to solvent of protein groups which modify water density, and (ii) "structural" contributions arising from changes in the volume of the protein itself. An experimental approach was developed to test the validity of the predictions based on model compound studies for catalytic conformational changes. By examining the effects of different solutes on the activation volumes of different enzymic reactions, we show that both sources of volume change provide significant contributions to the activation volume.
酶构象的变化通常伴随着体积的巨大变化。模型化合物研究表明,这些体积变化可能源于两个方面:(i)由于蛋白质基团暴露于溶剂的变化导致水密度改变而产生的“水合密度”效应,以及(ii)蛋白质本身体积变化引起的“结构”贡献。我们开发了一种实验方法来检验基于模型化合物研究对催化构象变化所做预测的有效性。通过研究不同溶质对不同酶促反应活化体积的影响,我们表明体积变化的这两个来源对活化体积都有显著贡献。