- 作者: 陳佩燁,梁甫呈,李中天,陳長謙*
- 作者服務機構: Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan, R.O.C.
- 中文摘要:
The role of the small exterior hydrophobic cluster (SEHC) in the strand region of the N-terminal
-hairpin of ubiquitin on the structural stability and the folding/unfolding kinetics of the protein have
been examined. We introduce a PheAla substitution at residue 4 in the strand region of the N-terminal
-hairpin of the ubiquitin. Apeptide with the same amino acid sequence as the first 21 residues of the mutated
ubiquitin has also been synthesized. The F4A mutation unfolds the hairpin structure of the peptide
segment without disruption of the turn. The same mutation does not seem to affect the overall structure,
but the stability of the mutated full-length protein decreases by approx. 2 kcal/mol. Kinetically, the entire
hairpin structure is implicated in the transition state during folding of the wild type protein. The rate of
refolding is retarded by the F4Amutation in ~80% of the protein molecules. The F4Asubstitution also increases
the unfolding rate of the protein by 10 fold. Thus the hydrophobic side-chain of Phe-4 not only
contributes to the stability of the hairpin, but also to the stability of the entire protein by forming a cluster
together with the hydrophobic residues on the C-terminal strand. - 英文摘要: --
- 中文關鍵字: Ubiquitin; Protein folding; Kinetics; Hairpin; Hydrophobic interaction.
- 英文關鍵字: --