<sup>15</sup>N−<sup>1</sup>H HSQC NMR Evidence for Distinct Specificity of Two Active Sites in <i>Escherichia coli</i> Glyoxalase I
Bibliographic record
Abstract
Much remains to be elucidated concerning the selectivity mechanism of supposedly identical active sites in oligomeric proteins. Glyoxalase I (GlxI) catalyzes the glutathione-dependent conversion of 2-oxoaldehydes to S-2-hydroxyacylglutathione derivatives. The E. coli GlxI is a Ni(2+)/Co(2+)-activated homodimeric protein containing two symmetric, and dually metallated active sites as characterized by X-ray structure determination. Nevertheless, kinetics and isothermal titration calorimetric (ITC) studies indicate that dimeric GlxI binds to metal ions in a ratio of 1:1 (one metal ion/one dimer) [ Clugston , S. L. , Yajima , R. , and Honek , J. F. ( 2004 ) Biochem. J. 377 , 309 - 316 ]. In the current study, we provide spectroscopic evidence for the nonequivalent metallation of GlxI by use of (15)N-(1)H HSQC NMR titration experiments. (15)N-(1)H HSQC NMR spectra reveal that the local conformations of the two active sites in homodimeric GlxI are initially asymmetric in the apo-form, resulting in functional differentiation, wherein only one active site binds to the Ni(2+) ion, and another active site is observed to be more selective for a potent inhibitor. The current results enhance our understanding of GlxI structure-function relationships and provide a potential new strategy for the development of small molecule inhibitors for this enzyme system.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".