Ahmad N, Srinivas V R, Reddy G B, Surolia A
Molecular Biophysics Unit, Indian Institute of Science, Bangalore.
Biochemistry. 1998 Nov 24;37(47):16765-72. doi: 10.1021/bi9811720.
The conformational stability of the homodimeric pea lectin was determined by both isothermal urea-induced and thermal denaturation in the absence and presence of urea. The denaturation profiles were analyzed to obtain the thermodynamic parameters associated with the unfolding of the protein. The data not only conform to the simple A2 if 2U model of unfolding but also are well described by the linear extrapolation model for the nature of denaturant-protein interactions. In addition, both the conformational stability (DeltaGs) and the DeltaCp for the protein unfolding is quite high, at about 18.79 kcal/mol and 5.32 kcal/(mol K), respectively, which may be a reflection of the relatively larger size of the dimeric molecule (Mr 49 000) and, perhaps, a consequent larger buried hydrophobic core in the folded protein. The simple two-state (A2 if 2U) nature of the unfolding process, with the absence of any monomeric intermediate, suggests that the quaternary interactions alone may contribute significantly to the conformational stability of the oligomer-a point that may be general to many oligomeric proteins.
在有无尿素存在的情况下，通过等温尿素诱导变性和热变性来测定同源二聚体豌豆凝集素的构象稳定性。分析变性曲线以获得与蛋白质解折叠相关的热力学参数。这些数据不仅符合简单的A2⇄2U解折叠模型，而且对于变性剂 - 蛋白质相互作用的性质也能用线性外推模型很好地描述。此外，该蛋白质解折叠的构象稳定性（ΔGs）和ΔCp都相当高，分别约为18.79千卡/摩尔和5.32千卡/（摩尔·开尔文），这可能反映了二聚体分子相对较大的尺寸（Mr 49000），并且也许还反映了折叠蛋白质中随之产生的更大的埋藏疏水核心。解折叠过程的简单二态（A2⇄2U）性质，且不存在任何单体中间体，表明仅四级相互作用可能对寡聚体的构象稳定性有显著贡献——这一点可能对许多寡聚蛋白质具有普遍性。
