To further characterize the intermediate state in the denaturation of tryptophan synthase alpha subunit from Escherichia coli, we have carried out differential scanning calorimetry in various concentrations of urea near pH 8.5. The heat capacity curve of the intermediate has no excess heat capacity nor any transition. This indicates that the intermediate is a thermodynamically denatured form. Although the intermediate retains significant CD signal in the far-uv region, the tertiary structure of the intermediate is disrupted as judged by the near-uv CD spectra and 1H NMR spectra in the aromatic region. This intermediate might be similar to a molten globule state. These results do not support our earlier proposal that the intermediate of the alpha subunit in the denaturation process retains an intact N-terminal domain, but that the C-terminal domain unfolds. Study holds ProTherm entries: 10020 Extra Details: additive : EDTA(1mM), tryptophan synthase alpha subunit; calorimetry; 1H NMR in the aromatic,region; intermediate in the denaturation process; molten globule
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:39 p.m.
|Number of data points||3|
|Proteins||Tryptophan synthase alpha chain ; Tryptophan synthase alpha chain|
|Assays/Quantities/Protocols||Experimental Assay: dCp ; Experimental Assay: dHcal ; Experimental Assay: Tm|
|Libraries||Mutations for sequence MERYESLFAQLKERKEGAFVPFVTLGDPGIEQSLKIIDTLIEAGADALELGIPFSDPLADGPTIQNATLRAFAAGVTPAQCFEMLALIRQKHPTIPIGLLMYANLVFNKGIDEFYAQCEKVGVDSVLVADVPVEESAPFRQAALRHNVAPIFICPPNADDDLLRQIASYGRGYTYLLSRAGVTGAENRAALPLNHLVAKLKEYNAAPPLQGFGISAPDQVKAAIDAGAAGAISGSAIVKIIEQHINEPEKMLAALKVFVQPMKAATRS|