Amino-Acid-Derived Oxazolidin-5-Ones as Chemical Markers for Schiff Base Formation in Glycation Reactions
Bibliographic record
Abstract
Imine or Schiff base formation is considered as a key event in the catalytic mechanisms of many enzymes and in certain biological transformations, including glycation. In this process, less stable amino-acid-derived Schiff bases rearrange into more stable ketoamines or Amadori products. Schiff bases are also stipulated to be stabilized through complexation with metal ions, or through intramolecular cyclization to form more stable and reversible cyclic isomers, such as oxazolidin-5-ones. These intermediates can be easily detected relative to Schiff bases due to their higher stability. In this study, high-resolution mass spectrometry and isotope labeling techniques were used to identify labile imines as their oxazolidin-5-one derivatives in heated reaction systems of glucose/alanine/FeCl2, including their 13C-labeled counterparts. The reaction mixtures were heated for 2h at 110 °C and were analyzed by high resolution qTOF/MS for the presence of masses corresponding to Schiff bases of α-alanine with short chain aldehydes that can be generated from glucose degradation and also for the incorporation of 13C-labeled atoms from 13C-3 alanine and 13C-U glucose. Analysis of the data has indicated that Schiff bases can indeed be detected in the form of oxazolidin-3-ones, when methanol is used as the solvent. Furthermore, it was discovered that metal-ion-stabilized Schiff bases, in addition to forming oxazolidin-3-ones, can also undergo aldol addition with short chain sugars and initiate oligomerization reactions, leading to the formation of dimeric or trimeric oxazolidin-3-one oligomers, as demonstrated by their characteristic MS/MS fragmentations.
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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 | 0.000 | 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".