Effect of temperature on the stereoselectivity of phospholipase D toward glycerol in the transphosphatidylation of phosphatidylcholine to phosphatidylglycerol
Bibliographic record
Abstract
In this study, the effect of temperature on the stereoselectivity of phospholipase D (PLD) toward the two primary hydroxyl groups of glycerol in the transphosphatidylation reaction of phosphatidylcholine to phosphatidylglycerol (PtdGro) was investigated. For this purpose, PLD from bacteria (Streptomyces septatus TH-2, S. halstedii subsp. scabies K6, and Actinomadura sp.) and cabbage were tested. At the reaction temperatures employed (0-60 degrees C), the proportions of the two PtdGro diastereomers, namely, 1,2-dioleoyl-sn-glycero-3-phospho-3'-sn-glycerol (R,R configuration) and 1 ,2-dioleoyl-sn-glycero-3-phospho-1'-sn-glycerol (R,S configuration), which were produced with PLD from Streptomyces TH-2 and Actinomadura sp., changed gradually from 50% R,R and 50% R,S at 50-60 degrees C to 70% R,R and 30% R,S at 0 degrees C. These alterations suggested that the stereoselectivity of the bacterial PLD toward the two primary hydroxyl groups of prochiral glycerol was significantly influenced by reaction temperature. PLD from Streptomyces K6 showed relatively little effect of temperature on stereoselectivity, giving 65-69% R,R in the temperature range of 60-10 degrees C examined. The plots of In ([R,R]/[R,S]) vs. 1/T gave good linear fits for these three bacterial PLD. No temperature effect was observed for cabbage PLD, which gave an almost equimolar mixture of the R,R and R,S diastereomers in the range from 0 to 40 degrees C. The temperature-dependent change in enantiomeric selectivity of the bacterial PLD promises potentially profitable commercial exploitation.
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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 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".