Kinetic studies of unmodified individual <i>Escherichia coli</i> β-galactosidase molecules in free solution
Bibliographic record
Abstract
Assays were performed on individual Escherichia coli beta-galactosidase molecules at 2 different concentrations of the substrate DDAO-beta-D-galactoside using a free zone capillary electrophoresis-based protocol with an in-laboratory-constructed instrument utilizing laser-induced fluorescence detection. In a typical run, 2 enzyme molecules were injected into the capillary. They were separated from each other by a brief period of electrophoresis and incubated on the capillary in the presence of the substrate. They were then mobilized on the capillary into a zone of substrate at a different concentration, re-incubated, and the product peaks mobilized past the detector . The relative change in activity as the concentration was increased differed between molecules, suggesting differences in Km. In a different experiment, the capillary was filled with on average 13 enzyme molecules per run, incubated, and the activities of the individual molecules determined. The shapes of the distribution curves of single molecule activities obtained at different concentrations of the substrate resorufin-beta-D-galactoside were indistinguishable, suggesting a homogeneous Km. To explain why individual enzyme molecules behaved as if they were heterogeneous with respect to Km but the population behaved as if it were homogeneous, theoretical Michaelis-Menten curves were constructed. The curves for populations with heterogeneous Km values were found to be indistinguishable from that of a homogeneous population.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 source (direct Gemma or distilled Codex), 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".