变构蛋白（别构蛋白）是具有变构剂行为的蛋白质。蛋白质分子空间结构和其性质及生理功能的关系也十分密切。此前一直认为不同的蛋白质，正因为具有不同的空间结构，因此具有不同的理化性质和生理功能。效应子分子被认为通过与一个变构点（与活性点明显不同）结合、从而诱导和稳定蛋白的某一特定构形状态来控制变构蛋白的活性。
一项新的研究表明，认为变构蛋白的活性纯粹由结构调控的观点应当予以修正，将来自蛋白动态的一个经常占支配地位的贡献包括进去。
Shiou-Ru Tzeng 和 Charalampos Kalodimos对与“降解物激活蛋白”（CAP）相结合的环AMP进行了定性。CAP是被经常用作变构模型的一个转录激活蛋白。他们出乎意料地发现，即便是当处在一个从结构上来讲没有活性的构形时，CAP也能被蛋白动态的变化所激活，以便与配体（DNA）结合。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 462, 368-372 (19 November 2009) | doi:10.1038/nature08560
Dynamic activation of an allosteric regulatory protein
Shiou-Ru Tzeng1,2 & Charalampos G. Kalodimos1,2
1 Department of Chemistry & Chemical Biology,
2 Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey 08854, USA
3 Correspondence to: Charalampos G. Kalodimos1,2 Correspondence and requests for materials should be addressed to C.G.K.
Allosteric regulation is used as a very efficient mechanism to control protein activity in most biological processes, including signal transduction, metabolism, catalysis and gene regulation1, 2, 3, 4, 5, 6. Allosteric proteins can exist in several conformational states with distinct binding or enzymatic activity. Effectors are considered to function in a purely structural manner by selectively stabilizing a specific conformational state, thereby regulating protein activity. Here we show that allosteric proteins can be regulated predominantly by changes in their structural dynamics. We have used NMR spectroscopy and isothermal titration calorimetry to characterize cyclic AMP (cAMP) binding to the catabolite activator protein (CAP), a transcriptional activator that has been a prototype for understanding effector-mediated allosteric control of protein activity7. cAMP switches CAP from the 'off' state (inactive), which binds DNA weakly and non-specifically, to the 'on' state (active), which binds DNA strongly and specifically. In contrast, cAMP binding to a single CAP mutant, CAP-S62F, fails to elicit the active conformation; yet, cAMP binding to CAP-S62F strongly activates the protein for DNA binding. NMR and thermodynamic analyses show that despite the fact that CAP-S62F-cAMP2 adopts the inactive conformation, its strong binding to DNA is driven by a large conformational entropy originating in enhanced protein motions induced by DNA binding. The results provide strong evidence that changes in protein motions may activate allosteric proteins that are otherwise structurally inactive.
