The pK's of Cardiolipins Are Altered by the Number and Position of their Specific Fatty Acid Esters
Bibliographic record
Abstract
We’ve confirmed that the 2 phosphate groups of tetrastearoyl‐cardiolipin (CL) have distinctly different pK values, one above neutrality. Although CL's chemical structure, suggests that it has 2 identical negative charge at neutral pH, our data shows it does not. Previously (Kates et al. (1993) Lipids , 28 , 877–882), showed the pK 2 was >8.0 with the tetrastearoyl CL, we have examined the dependence of the titration of cardiolipin on the number and nature of the acyl chains. The high pK 2 varies, with the chainlength and desaturation of the chains on the lipid. As the chain structure is varied, the pK 2 ranges from 3–8. The latter dominates with C 18 chains. Short chains yield lower pK 2 's e.g., E. coli CL. Typical mitochondrial CL's have 4 linoleoyl chains. The high pK 2 is explained by a bicyclic, H‐bonded conformation of CL's headgroup. Evidence for this has been provided by showing that deoxycardiolipin, lacking the central OH of the connecting glycerol, has a pK 2 below 4.0. This data supports the proposal that CL has a role in ATP synthesis by providing a pool of protons on both sides of the membrane for proton pumping (Haines & Dencher (2003) FEBS Lett. 528 , 35–39). Our results show the high pK 2 , present in tetramyristoyl cardiolipin is missing in myristoyl lysocardiolipin. A chemical test for the often fatal Barth's Syndrome is lysocardiolipin. Our results may be relevant to this genetic disease which may have defective ATP synthesis.
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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 | 0.000 | 0.001 |
| 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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".