Structure and mechanism of LGK: insights into the bioconversion of levoglucosan
Bibliographic record
Abstract
Lignocellulosic biomass is an abundant source of carbohydrates that can be used for the production of biofuels. Additional processing of biomass-derived sugars arises from the fact that the most abundant sugar product from biomass pyrolysis is the unusual anhydro-ring containing sugar, levoglucosan (LG). LG does not fall within the native substrate range of commonly used biocatalysts such as Escherichia coli and Saccharomyces cerevisiae. However, LG can be further converted to glucose-6-phosphate through the activity of the sugar kinase known as levoglucosan kinase (LGK), which has been isolated from a variety of fungal sources. Integration of recombinant LGK from Lipomyces starkeyi into an engineered ethanologenic Escherichia coli strain has been shown to allow for the utilization of LG as the sole carbon source for ethanol production [1]. However, challenges associated with effective utilization of LG include a high Km of LGK for LG, and the relatively low activity of LGK at physiological pH. In addition to the practical applications of LGK for biofuel production, the enzyme is an exceptional target for structural and mechanistic studies since it appears to possess dual hydrolase and kinase functionality. In order to gain a better understanding of the structure and mechanism of LGK, we have crystallized and determined several high-resolution X-ray structures of Lipomyces starkeyi LGK bound to reaction substrates and products. We have also recently collected low-resolution neutron diffraction for an LGK crystal, and further optimization of LGK crystals is currently underway to improve crystal size and diffraction. Neutron diffraction will reveal the protonation states of key residues in the active site of LGK and provide highly detailed information about hydrogen bonds, including water-bonding interactions. The rational design of new LGK constructs will be used to improve applications of this enzyme towards levoglucosan derived biofuel production.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| 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".