Polymer brush-coated enzyme carriers:an oral therapy approach for phenylketonuria
Bibliographic record
Abstract
Phenylketonuria (PKU) is an inherited disorder that compromises the metabolism of the essential amino acid phenylalanine (Phe). It is characterized by high blood- and brain-Phe concentrations, which can lead to severe neurological and developmental disorders when left untreated. A restrictive Phe-free diet is the primary treatment option. Pharmacological treatments, such as a pegylated Phe ammonia lyase (PAL), are available only to a few patients and are associated with countless drawbacks. Given these limitations, individuals with PKU would benefit from a universal non-invasive therapy. Herein, a formulation for the oral delivery of an enzyme substitution therapy to consume Phe in the intestine before its absorption is envisioned. As a model, the activity of an analogous enzyme to PAL, histidine ammonia-lyase (HAL) from the extremophile Thermoplasma acidophilum (Ta), was characterized in terms of acid tolerance. TaHAL fused to the maltose-binding protein (MBP) solubility enhancer tag showed an impressive activity recovery after exposure to pH 2.8 following neutralization. Furthermore, immobilization of MBP-TaHAL into liposomes as possible enzyme carriers was considered but proved inefficient with the loss of the catalytic function. Alternatively, silica particles were coated with poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) brushes prepared by grafting-to and grafting-from methods to achieve high enzyme loading. For comparison, particles functionalized with monolayers of the same polymer were included. The polymer-coated particles and subsequent electrostatic adsorption of MBP-TaHAL were characterized in terms of polymer and protein deposition, surface charge, and enzyme activity. The particles coated with brushes showed superior enzyme adsorption and activity compared to monolayers. Grafted from brushes offered the most suitable environment for immobilization of MBP-TaHAL, evidenced by a high protein binding, which translated into more than 75% activity compared to the bulk enzyme. Although protecting this assembly against proteases remains challenging, the immobilization of MBP-TaHAL allows for the upconcentration and reuse of the enzyme. In conclusion, this work reports particles coated with polymer brushes that work as carriers for an acid-tolerant enzyme from extremophiles. This catalytically active carrier offers a possibility for further formulation towards an oral treatment of PKU with the conversion of the substrate-specificity of HAL from histidine to Phe and a strategy to immobilize other therapeutic-relevant enzymes.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".