Purification, crystallization and preliminary X-ray analysis of a μ-like calpain
Bibliographic record
Abstract
The X-ray structure of m-calpain in the absence of Ca(2+) has been described, but it has not been possible to obtain sufficient mu-calpain for structure determination. Comparison of the two structures is of interest in attempting to understand their different Ca(2+) requirements. Here, the crystallization in the absence of Ca(2+) of an inactive mutant hybrid calpain (MW approximately 100 kDa), which contains 85% of the rat mu-calpain sequence and is well expressed in Escherichia coli, is described. The properties of this calpain in its active form and particularly its Ca(2+) requirement are close to those expected for wild-type mu-calpain. Clusters of plate-shaped crystals were obtained by vapour diffusion with polyethylene glycol (M(r) approximately 6000) as precipitating agent in the presence of detergent. The crystals diffract to a resolution of 2.7 A at a synchrotron source. The space group is P2(1), with unit-cell parameters a = 72.7, b = 184.6, c = 86.3 A, beta = 100.7 degrees. There are two molecules in the asymmetric unit, corresponding to a solvent content of 57.1%.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".