Intrachain diffusion in a protein loop fragment from carp parvalbumin
- 作者：Krieger ; Florian ; Fierz ; Beat ; Axthelm ; Fabian ; Joder ; Karin ; Meyer ; Dominique ; Kiefhaber ; Thomas
- 关键词：Protein folding ; Chain dynamics ; Intrachain diffusion ; Triplet脙脙脙脙脙脙triplet energy transfer ; Carp-parvalbumin ; Calcium-binding
- 刊名：Chemical Physics
- 出版年：2004
- 期刊代码：18_03010104
- 类别：ch
- 出版时间：December 27, 2004
- 卷：307
- 期：2-3
- 页码：209-215
- 文件大小：360 K
摘要
During protein folding a polypeptide chain has to form specific intrachain interactions starting from an ensemble of unfolded conformation. Thus, intrachain diffusion in unfolded polypeptide chains can be regarded as an elementary step in protein folding, which should determine the dynamics of the early stages in the folding process. We have previously applied exothermic triplet芒芒芒triplet energy transfer from xanthone to naphthalene to determine rate constants for intrachain end-to-end contact formation in unstructured homo-polypeptide chains. Here we show that the method can be applied to determine absolute rate constants for intrachain diffusion in natural loop sequences, if they are free of methionine, tryptophan and tyrosine. We measured the rate of loop formation in an 18 amino acid polypeptide chain corresponding to a natural loop sequence from carp muscle 芒芒-parvalbumin (residues 85芒芒芒102). Contact formation shows single exponential kinetics with a time constant (芒芒