Enzymatic hydrolysis of β-lactam antibiotics at low pH in a two-phase "aqueous solution - water-immiscible organic solvent" system
Bibliographic record
Abstract
The application of the two-phase "aqueous solution water-immiscible organic solvent" system is suggested not for effective biocatalytic synthesis, but for hydrolytic purposes. Enzymatic hydrolysis of benzylpenicillin and N-phenylacetamidodesacetoxycephalosporanic acid to corresponding antibiotic nuclei 6-aminopenicillanic and 7-aminodesacetoxycephalosporanic acids in a two-phase waterbutylacetate system at pH 34 is proposed as an alternative to the biocatalytic hydrolysis in an alkaline medium. An experimental study has been performed and a model has been developed, which describes the influence of pH, phase volume ratio, thermodynamic constants, and initial antibiotic concentration on the effectiveness of their hydrolysis in a two-phase "aqueous solution water-immiscible organic solvent" system. The thermodynamic evaluation of penicillin G and 7-phenylacetamidodesacetoxycephalosporanic acid hydrolysis at low pH in a two-phase aqueous solution water-immiscible organic solvent system has demonstrated high practical potential. The suggested approach allows for the exclusion of several technological steps during the transformation of natural β-lactam antibiotics to their semi-synthetic analogues: alkaline extraction of the biosynthetic antibiotic from butylacetate followed by its enzymatic hydrolysis at pH 7.58.0 and further acidification of the reaction mixture, which results in the precipitation of the antibiotic nucleus. Experimental observations also revealed a specific feature of this process: the kinetic supersaturation of the antibiotic nucleus slows down the attainment of the equilibrium, which should be taken into account when further developing this approach.Key words: enzymatic hydrolysis, β-lactam antibiotic nuclei, two-phase systems, supersaturation, penicillin acylase.
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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 | 0.000 | 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 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".