Liang H, Terwilliger T C
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637.
Biochemistry. 1991 Mar 19;30(11):2772-82. doi: 10.1021/bi00225a006.
The guanidine hydrochloride (GuHCl)-induced denaturation of the gene V protein of bacteriophage f1 has been studied, using the chemical reactivity of a cysteine residue that is buried in the folded protein and the circular dichroism (CD) at 211 and 229 nm as measures of the fraction of polypeptide chains in the folded form. It is found that this dimeric protein unfolds in a single cooperative transition from a folded dimer to two unfolded monomers. A folded, monomeric form of the gene V protein was not detected at equilibrium. The kinetics of unfolding of the gene V protein in 3 M GuHCl and the refolding in 2 M GuHCl are also consistent with a transition between a folded dimer and two unfolded monomers. The GuHCl concentration dependence of the rates of folding and unfolding suggests that the transition state for folding is near the folded conformation.
利用折叠蛋白中埋藏的半胱氨酸残基的化学反应性以及211和229nm处的圆二色性（CD）作为折叠形式的多肽链比例的度量，研究了盐酸胍（GuHCl）诱导的噬菌体f1基因V蛋白的变性。发现这种二聚体蛋白以单一的协同转变从折叠二聚体展开为两个未折叠的单体。在平衡状态下未检测到基因V蛋白的折叠单体形式。基因V蛋白在3M GuHCl中的展开动力学和在2M GuHCl中的重折叠动力学也与折叠二聚体和两个未折叠单体之间的转变一致。折叠和展开速率对GuHCl浓度的依赖性表明，折叠的过渡态接近折叠构象。
