How do we get usable USP10 protein faster?
The bottleneck depends on the construct. 368–798 produces usable protein; 359–798 first loses material at soluble recovery; full-length failure can begin at expression or soluble recovery, then recur during warm cleavage and handling.
The notebooks show where these preparations failed. The evidence scan adds public production routes that support—or limit—the next move.
What the notebooks show
Internal preparation records only: 368–798 is not presently failing; 359–798 first loses material at soluble recovery; full-length failure begins at expression, soluble recovery or warm cleavage and handling.
| Production stage | 368–798 | 359–798 | Full length |
|---|---|---|---|
| Expression | Established. Documented BL21 expression with the successful pOPIN B route. | Established. Expression occurred, but a large fraction was insoluble in the first recurrent failure pattern. | Possible, batch-dependent. Internal bacterial preparations ranged from weak or ambiguous expression to no detectable soluble full length. |
| Recovery and purification | Known good. Affinity capture, cleavage, ResS and SEC produced about 25 mg total: 3.7 mL at 6.76 mg/mL. | First loss: soluble recovery. In a later 12 L run, a 1 mL capture was also insufficient. High salt during overnight cleavage/dialysis avoided visible precipitation, and His-tagged material bound Resource Q better in that preparation. | First loss varies. Direct bacterial preparations can fail at soluble recovery. When partner-associated material formed, a one-hour room-temperature cleavage/handling step caused degradation; SEC later exposed the remaining heterogeneity. |
| Homogeneity and stability | Best supported. The April 2022 batch was described as the purest yet, with duplicate Tycho support strongest in tested neutral to alkaline conditions. A separate 2020 low-salt, pH 8 dialysis precipitation was reversible. | Clean yield was small. Of 7.33 mg total SEC recovery, only 1.09 mg was labelled super clean; 5.18 mg was degraded. | Not demonstrated internally. Recovered material remained degraded, dirty or heterogeneous. G3BP1 association did not provide a generic stability rescue. |
| Functional QC | Established. The successful stock was active in a controlled diUb panel after purification and physical QC. | Activity survived in part. Clean and degraded preparations reacted with UbPA; probe-reactive lower bands and impurities do not count as clean usable product. | Not established internally. The direct full-length versus 368–798 comparison had assay errors and unequal loading, so no concentration-matched functional result survives QC. |
What the evidence scan adds
Public evidence does not explain the notebook failures, but it supplies three useful production precedents.
376–798 catalytic regionBL21(DE3), low-temperature overnight expression, Ni-NTA, cold cleavage, reverse Ni-NTA and SEC produced active material at 20 mg/mL. This is an adjacent-boundary analogy, not exact 359–798 or 368–798 validation.
Tagged full lengthPublic His- and GST-tagged bacterial preparations reached activity assays. This supports inspecting intact tagged material before cleavage, but the papers do not report yield, SEC, stability or homogeneity.
Baculovirus routeAn active His-USP10 preparation establishes fallback feasibility. Its exact boundary, insect cell line, yield and physical QC are not reported, so it is not a validated rescue.
What to do next
368–798 or flexible choiceReproduce the known-good 368–798 route and use it as the process control.
359–798 requiredAddress soluble recovery and capture first. Use adequate affinity capacity, preserve the recorded high-salt and cold handling, and retain the His tag through polishing unless tag-free protein is required.
Full length requiredInspect intact tagged material before cleavage, keep it cold, remove the room-temperature cleavage hold, and stop at the first destructive transition. Consider baculovirus only if the corrected bacterial route still fails.
For every path: verify construct identity, then sample soluble lysate, affinity fractions, pre/post-cleavage and SEC so the first loss is visible.