Synthesis and Characterization of a Long, Rigid Photoswitchable Cross‐Linker for Promoting Peptide and Protein Conformational Change
Bibliographic record
Abstract
Azobenzene-based photoswitchable compounds can be use to photocontrol a variety of biochemical systems. In some cases, their effectiveness may be limited by the size of the conformational change that the switch undergoes. To produce an azobenzene photoswitch that undergoes a large end-to-end distance change upon isomerization, we synthesized 3,3'-diazene-1,2-diylbis{6-[2-sulfonato-4-(chloroacetylamino)phenylethynyl]benzene sulfonic acid} (DDPBA). This long, rigid, water-soluble, thiol-reactive cross-linker undergoes an end-to-end distance change of approximately 13 A upon isomerization. DDPBA was successfully cross-linked to peptides through cysteine side chains. The photoswitch undergoes trans-to-cis photoisomerization maximally when irradiated at 400 nm, although the efficiency of production of the cis isomer is lower than for simpler azobenzenes. Under steady-state illumination conditions, the percentage of cis form produced increases as temperature increases; approximately 56 % cis is obtained at 60 degrees C. Thermal relaxation occurs with a half-life of approximately 75 min at room temperature. When DDPBA was attached to an alpha-helical peptide with two cysteine residues at i and i+14 positions, an increase in helix content was observed after photoirradiation. When cross-linked to another peptide with two cysteine residues spaced at i and i+21 positions, a decrease in helix content after trans-to-cis isomerization was observed. Due to the small percentage of cis form produced under the experimental conditions, the CD signal changes were small. However, the large structural change upon photoisomerization provided by this cross-linker can potentially be used to photoswitch other biochemical systems.
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) | 0.000 | 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".