Computational follow-up on the Rowan/Boltz side: what seems real so far, what changed, and what to do next
This is a focused follow-up on the dopamine-quinone / NQO1 P187S thread, with the goal of turning the Rowan runs and the newer Boltz panels into a small, defensible next-step plan rather than another sprawling ligand zoo.
What changed in the overall picture
The strongest synthesis right now is:
- P187S does not look like a dead quinone pocket.
- The main defect still looks more like a weakened or less coherent holo-state than total substrate exclusion.
- The mutant seems to struggle most with oxidized dopamine-quinone stress states.
-
Reduced downstream states look easier for the mutant to accommodate than the harsher upstream quinone states.
- The chemistry is now splitting into separate branches rather than one unified “dopamine damage” problem.
The most useful way to phrase the current mechanistic read is:
P187S seems worst at maintaining a productive flavin-supported state under oxidized quinone stress, while more reduced downstream branch intermediates are comparatively better tolerated.
That is not a claim of restored catalytic detox and not a claim about true affinity. It is a structural/coherence claim based on the current Boltz outputs.
Important interpretation guardrail
The Boltz metrics being used here are mostly pose/interface coherence proxies, not direct binding free energies and not catalytic proof.
When I say one state looked “cleaner,” I mean things like:
- higher
ligand_iptm
- higher
complex_iplddt
- lower
complex_ipde
- tighter probe/cofactor geometry where measured
So the right language is:
- better structural compatibility / coherence
- weaker or stronger holo-state organization
- more or less plausible coexistence state
Not:
- tighter binding in a physical affinity sense
- proven detox
- proven rescue of whole-cell NQO1 function
NQO1 P187S branch results: what held up
1. Flavin-state dependence still matters a lot
The earlier flavin matrix kept pointing to the same headline:
- flavin state matters more than just adding more quinones
- different ligand branches behave differently depending on whether the system is in FAD / FADH2 / FMN / FMNH2-like states
This supports the broader idea that the mutant’s defect is tightly tied to the cofactor-supported state, not just to which dopamine-derived ligand is present.
2. Extra branch probes sharpened the oxidized-vs-reduced story
The extra NQO1 branch probes gave a useful ranking:
- 5,6-dihydroxyindole
- leukoaminochrome
- 5,6-indolequinone
- explicit DOPAC o-quinone
The important interpretation was not “the mutant loves 5,6-dihydroxyindole.” It was:
- the mutant is less stressed once the branch has already moved away from strongly oxidized quinone states
-
reduced/catechol-like downstream states are easier for P187S than oxidized quinone-heavy states
- explicit DOPAC o-quinone remained exploratory and weak compared with the cleaner downstream branch probes
3. Curated reruns clarified the microstate picture
The curated standard-5 reruns tightened the carry-forward set for P187S + FAD:
-
Aminochrome, protonated = strongest oxidized stress-state carry-forward ligand
-
Dopamine o-quinone, neutral = weakest state by a wide margin, but still worth carrying forward as the harsh upstream stress baseline
-
5,6-dihydroxyindole, neutral = strongest reduced downstream tolerated state
-
5,6-indolequinone, protonated = useful downstream oxidized comparator
-
Leukoaminochrome, neutral = better than protonated in the stricter rerun
That means the current core NQO1 panel is no longer just “highest scores.” It now spans a usable oxidation-state axis:
- upstream oxidized
- cyclized oxidized stress state
- reduced aminochrome branch
- downstream oxidized indole branch
- downstream reduced indole branch
GSTM2 + GSH branch: what it looks like now
The GSTM2 + GSH panel became more interpretable after the structure-level pass.
The ranking stayed:
- GSTM2 + GSH + 5-S-cysteinyl-dopamine
- GSTM2 + GSH + aminochrome
- GSTM2 + GSH + dopamine o-quinone
But the structure-level read clarified what those rankings probably mean:
-
5-S-cysteinyl-dopamine looks like the best product / damage-branch accommodation state, not automatically a catalytic substrate claim
-
dopamine o-quinone is geometrically coherent as a GSTM2-associated state, but it sits too far from GSH to look like a convincing conjugation-coupled state in the current pass
-
aminochrome sits between them as a plausible but looser stress-associated state
So the GSTM2 branch should currently be interpreted as:
-
damage-branch accommodation / trapping plausibility, not final catalytic ranking
- useful for asking whether GST/GSH chemistry can compensate downstream of defective NQO1 handling
Rowan side: what succeeded and what was learned
The Rowan campaign turned out to be useful mainly for microstate cleanup, conformer/tautomer handling, and reactivity triage, not as a magic one-stop answer.
Rowan workflows that were useful
These were either launched or meaningfully clarified the next stage:
- tautomer search
- conformer search
- Fukui panel
- descriptor-style triage on selected diet-derived compounds
- microstate logic for the quinone panel
Rowan plan limitations and blockers
What became clear:
- the free Rowan plan does not expose macropKa, so that workflow is not currently available on that plan
-
tautomer, redox, and Fukui were the supported/usable workflows on the current plan
-
double-ended TS / IRC is blocked unless reactant and product files preserve identical atom ordering
So the Rowan bottlenecks are now practical rather than conceptual:
- use only workflows the plan can actually run
- preserve atom ordering if transition-state workflows are going to be used later
What Rowan was already useful for
Even before everything finished, Rowan was already useful for deciding that:
-
aminochrome remains the cleanest parent Boltz input
-
dopamine o-quinone needs careful microstate handling
-
DOPAC o-quinone should be treated cautiously and remains exploratory
-
NAC looks chemically sane enough to keep in the trapping panel
Small-molecule rescue / compensation candidates: where things stand now
A focused rescue/compensation batch changed the small-molecule picture in a useful way.
NQO1 P187S + FAD side
The clean conclusion now is:
-
Cysteamine is the current structure winner
-
Piceatannol is still the score winner, but structurally much looser
The key difference is important:
-
Piceatannol may be acting like a higher-scoring but looser polyphenol pocket occupant
-
Cysteamine looks more like a small sulfur-containing compatibility / direct-trap candidate
The current interpretation is that cysteamine is the better NQO1-side rescue-style / coexistence lead from this panel.
GSTM2 + GSH side
The clean conclusion now is:
-
NAC remains the better practical compensation lead
-
Cysteinylglycine may look tighter geometrically in one sense, but NAC keeps the better overall score with similarly stable GSH geometry
So on the GSTM2/GSH branch, NAC is still the better compensation candidate.
Ternary/coexistence pass: what that clarified
The ternary structure pass made the candidate split more explicit:
-
NAC + dopamine o-quinone keeps NAC coherent, but the quinone itself remains loose
-
Cysteamine + dopamine o-quinone gives the cleaner NQO1-side coexistence state
That means cysteamine is now looking less like a generic antioxidant and more like a chemically serious small sulfur-containing NQO1-side lead.
At the same time, NAC still looks better placed as the GSTM2 + GSH compensation-side lead.
That is a useful separation of roles rather than a contradiction.
What this does not mean yet
A few things are still not shown:
- It does not prove cysteamine restores P187S to WT function.
- It does not prove true catalytic detox for any of these Boltz states.
- It does not solve the whole-cell problem that P187S is low-abundance, weakly holo-loaded, and short-lived.
- It does not mean the best-looking reduced downstream states are necessarily the states the mutant can efficiently make.
That last point matters a lot.
If P187S “tolerates” a reduced downstream state like 5,6-dihydroxyindole, that means:
- the surviving mutant holo enzyme can likely accommodate that state more coherently
It does not automatically mean:
- the mutant can efficiently reduce the upstream oxidized quinone into that state
- the mutant has restored meaningful net cellular detox capacity
A good rule of thumb is:
current Boltz results mostly probe per-molecule competence of the surviving holo pool, not total cellular detox throughput.
The most useful branch split going forward
At this point the project has effectively split into three separate branches.
1. NQO1 redox-stress branch
Core question:
- how does P187S behave across oxidized vs reduced dopamine-derived branch intermediates?
Current core states:
- aminochrome, protonated
- dopamine o-quinone, neutral
- leukoaminochrome, neutral
- 5,6-dihydroxyindole, neutral
- 5,6-indolequinone, protonated
2. GSTM2 + GSH compensation / trapping branch
Core question:
- what looks like plausible GSH-associated compensation, accommodation, or product-side trapping?
Current core states:
- GSTM2 + GSH + aminochrome
- GSTM2 + GSH + dopamine o-quinone
- GSTM2 + GSH + 5-S-cysteinyl-dopamine
- follow-up compensation lead: NAC
3. ALDH / aldehyde branch
Core question:
- what happens on the DOPAL / DOPAC toxicity side that is adjacent to, but not the same as, the NQO1 quinone problem?
This should now be treated as a separate toxicity branch, not forced back into the NQO1 pocket story.
The explicit trapped-state panel is the right next test
The most important immediate follow-up is the explicit trapped-state comparison:
- free candidate + quinone
- versus
- inferred sulfur-adduct / trapped endpoint
Why this matters:
It distinguishes between three different possibilities that are easy to blur together.
A. Free-candidate coexistence only
The candidate sits near the quinone and looks structurally compatible, but may not really trap anything.
B. True sacrificial-trap behavior
The explicit trapped/adduct endpoint also looks coherent. That would make the case much stronger for a real direct chemical sink.
C. Decoy compatibility
The free state looks nice, but the trapped endpoint looks bad. That would suggest a compatibility modulator more than a true detox route.
This is especially important for cysteamine right now.
Immediate next-step plan
Highest-priority computational steps
-
Run the explicit trapped-state Boltz panel
- especially for cysteamine and NAC versus dopamine o-quinone / aminochrome-derived states
-
Keep the NQO1 P187S carry-forward set narrow
- aminochrome, protonated
- dopamine o-quinone, neutral
- leukoaminochrome, neutral
- 5,6-dihydroxyindole, neutral
- 5,6-indolequinone, protonated
-
Keep the GSTM2 + GSH branch narrow
- aminochrome
- dopamine o-quinone
- 5-S-cysteinyl-dopamine
- NAC as the compensation lead
-
Do not let DOPAC o-quinone dominate the next stage
- keep it in an exploratory side bucket, not the headline matrix
-
Convert Rowan outputs directly into the corrected Boltz rerun matrix
- especially where microstate handling still changes the input choice
After that
Only once the explicit trapped-state and corrected Boltz reruns are done:
- take a tiny finalist set into explicit-solvent MD
- do not expand the ligand list again before getting dynamics on the shortlist
What I think the best current shortlist is
NQO1-side shortlist
- Aminochrome, protonated
- Dopamine o-quinone, neutral
- Leukoaminochrome, neutral
- 5,6-dihydroxyindole, neutral
- 5,6-indolequinone, protonated
-
Cysteamine as the best current rescue-style small-molecule lead
-
Piceatannol only as a secondary comparator, not the main mechanistic lead
GSTM2-side shortlist
- Aminochrome
- Dopamine o-quinone
- 5-S-cysteinyl-dopamine
-
NAC as the best current compensation lead
The cleanest current bottom line
Here is the version I would stand behind right now:
The current Rowan + Boltz follow-up reinforces a model in which NQO1 P187S is not a dead quinone pocket but a weakened flavin-supported holo system that is most stressed by oxidized dopamine-quinone states. Reduced downstream branch intermediates are comparatively better tolerated. On the rescue/compensation side, cysteamine is now the best NQO1-side small sulfur lead by structure, while NAC remains the strongest GSTM2 + GSH compensation lead. The immediate next step is to compare free-candidate coexistence states against explicit sulfur-trapped endpoints and then carry only a tiny finalist set into MD.
Specific questions where outside input would still be useful
- Is the explicit trapped-state panel the right next computational discriminator for cysteamine and NAC, or is there a better way to force the “compatibility vs true trap” distinction?
- For the MD shortlist, which 4 to 6 states would people prioritize first?
- Is there a more chemically faithful way to represent the sulfur-adduct endpoints for dopamine o-quinone and aminochrome in this pipeline?
- On the GST side, are there better neuronal/astrocytic GST isoforms than GSTM2 to include in the next pass?
- For the ALDH branch, which minimal DOPAL / ALDH1A1 / ALDH2 panel would add the most without blowing up scope?
Final caution
Nothing here should be read as a clinical recommendation. This is still a computational triage / mechanism-building workflow. The strongest current outputs are about state compatibility, microstate sensitivity, and branch plausibility, not proven in-cell rescue.