Lehle, Karla and Kohnert, Ulrich and Stern, Anne and Popp, Fritz and Jaenicke, Rainer (1996) Effect of disulfide bonds on the structure, function, and stability of the trypsin/tPA inhibitor from Erythrina caffra: Site-directed mutagenesis, expression, and physiochemical characterization. NATURE BIOTECHNOLOGY, 14 (4). pp. 476-480. ISSN 1087-0156, 1546-1696
Full text not available from this repository.Abstract
Erythrina trypsin/tPA inhibitor (ETI) from the seeds of Erythrina caffra retains its native structure and inhibitory function after reducing its two disulfide bonds. In order to elucidate the specific role of these crosslinks, alanine residues were substituted for cysteines after cloning the gene in Escherichia coli. Expression of the recombinant inhibitor and the substitution mutants, C83A, CC39,83AA, and CC132,139AA, led to inclusion bodies. After solubilization in guanidinium-chloride (GdmCl)/dithiothreitol and oxidation in glutathione buffer, activity could be recovered at yields up to 80%. The mutant proteins exhibit full inhibitory function without detectable alterations of their native structure. However, their stability is reduced: at acid pH, where the oxidized natural inhibitor retains its native structure, the reduced wildtype protein and the mutants undergo at least partial denaturation, reflected by decreased pH ranges of stability: pH 5-7 for the reduced inhibitor, pH 2.5-8.5 for CC132,139AA, and pH 3.5-8.5 for C83A and CC39,83AA. Urea and GdmCl denaturation at pH 7 show hysteresis for both the oxidized inhibitor and the double mutant CC132,139AA. In contrast, the reduced protein and the other mutants exhibit true equilibrium transitions at pH 7, with urea half-concentrations of 0.9 M and 1.9 M and GdmCl half-concentrations of 0.5 M and 1.0 M, respectively. The stability of Erythrina trypsin/tPA inhibitor follows the sequence: oxidized ETI > CC132,139AA > CC39,83AA and C83A > reduced ETI.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TISSUE PLASMINOGEN-ACTIVATOR; PROTEINASE-INHIBITORS; ESCHERICHIA-COLI; PURIFICATION; SEEDS; disulfide bonds; Erythrina; stability; tissue plasminogen activator; trypsin inhibitor |
| Subjects: | 500 Science > 540 Chemistry & allied sciences 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 02 Nov 2023 07:44 |
| Last Modified: | 02 Nov 2023 07:44 |
| URI: | https://pred.uni-regensburg.de/id/eprint/51845 |
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