Ultrafast Events in the Folding of Ferrocytochrome c

R Kumar, NP Prabhu, AK Bhuyan - Biochemistry, 2005 - ACS Publications
Biochemistry, 2005ACS Publications
Laser flash photolysis and stopped-flow methods have been used to study the dynamic
events in the micro-to millisecond time bin in the refolding of horse ferrocytochrome c in the
full range of guanidine hydrochloride concentration at pH 12.8 (±0.1), 22° C. Under the
absolute refolding condition, the earliest relaxation time of the unfolded protein chain is less
than 1 μs. The chain then undergoes diffusive dynamics-mediated contraction and
expansion, in which intrapolypeptide ligands make transient contacts with the heme iron …
Laser flash photolysis and stopped-flow methods have been used to study the dynamic events in the micro- to millisecond time bin in the refolding of horse ferrocytochrome c in the full range of guanidine hydrochloride concentration at pH 12.8 (±0.1), 22 °C. Under the absolute refolding condition, the earliest relaxation time of the unfolded protein chain is less than 1 μs. The chain then undergoes diffusive dynamics-mediated contraction and expansion, in which intrapolypeptide ligands make transient contacts with the heme iron, giving rise to two distinct kinetic phases of ∼0.4 and ∼3 μs. Under moderate to absolute refolding conditions, the rates of these processes show little dependence on the denaturant concentration, indicating the absence of structural element in the incipient or the relaxed state. Chain expansion and contraction events continue until the polypeptide finds a stable and supportive transition state. The crossing of this transition barrier, which rate-limits the folding of alkaline ferrocytochrome c, is characterized by a stopped-flow measured time constant of ∼3 ms in aqueous solvent. Observed kinetics thus implicate no submillisecond folding structure. The folding kinetics is effectively two state in which the unfolded polypeptide first relaxes to an unstructured chain and then crosses over a late rate-limiting barrier to achieve the native conformation. The experimentally observed rates as a function of guanidine hydrochloride concentration have been simulated by numerically calculated microscopic rates of a simple kinetic model that captures the essential features of folding.
ACS Publications
以上显示的是最相近的搜索结果。 查看全部搜索结果

Google学术搜索按钮

example.edu/paper.pdf
搜索
获取 PDF 文件
引用
References