Phosphorylation by Alkaline Phosphatase: Immobilization and Synthetic Potential
Bibliographic record
Abstract
Phosphatases (AP, E.C. 3.1.3.1) are hydrolytic enzymes that naturally hydrolyse phosphomonoesters but in a so-called transphosphorylation reaction these enzymes are also able to transfer a phosphate group from phosphorylated compounds to alcoholic functions. This transphosphorylation catalysed by acid phosphatases using pyrophosphate as a phosphate donor has been studied in some detail. However, the acidic pH optimum of these enzymes limits some of their applications. The catalytic features of alkaline phosphatase are similar to the acid phosphatases and its alkaline pH optimum suggests a possible application of this enzyme in phosphorylation reactions which need to be carried out at higher pH. Here we explore the synthetic potential of bovine intestine alkaline phosphatase (AP) in the phosphorylation of dihydroxyacetone (DHA) and glycerol using pyrophosphate (PPi) as phosphate donor. The phosphorylated compounds are intermediates in two multi-enzymatic cascade reactions for the synthesis of carbohydrates. The yields of dihydroxyacetone phosphate (DHAP) and glycerol-1-phosphate at pH 8 (2.6 mM and 2.2 mM, respectively) were comparable to the results obtained with the acid phosphatases at pH 4. Nevertheless, when the cascade reactions were carried out at pH 8, very low conversions were measured due to inactivation of the alkaline phosphatase by the product phosphate. To circumvent this inhibition, the alkaline phosphatase was immobilized on aldehyde-activated beads (Sepabeads EC-HA). The immobilization greatly diminished the inhibition by phosphate, and the immobilized alkaline phosphatase at pH 8 gave the same conversions in the cascade reaction starting from DHA as obtained with the acid phosphatase at pH 6. However, the immobilized enzyme was active for only one catalytic cycle and the beads could not be reused.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".