Reaction mechanisms
Why acetaldehyde kills the DERA aldolase
Open access · cc by · source: Europe PMC
Crotonaldehyde, the acetaldehyde aldol product, covalently bridges catalytic K167 to nearby C47; a C47M mutant survives 300 mM acetaldehyde.
How this study connects
Role on claims
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Mechanism papers use NMR as one reporter among several. ¹³C NMR plus crystallography showed how crotonaldehyde inactivates DERA via K167 and C47; isotope-resolved NMR with ThT and cryo-TEM showed Aβ40 and Aβ42 forming separate homomolecular fibrils after mixed nucleation; ¹H NMR Ka ≈ 75 558 M⁻¹ for DMA binding tracked allosteric opening of a Pt tweezer catalyst.
Evidence for the claim as stated.
HPLC-adjacent assays in this set also include enzyme activity workups. E. coli DERA is irreversibly inactivated after 200–300 mM acetaldehyde; crotonaldehyde inhibits more than 100-fold more potently (1 mM, <1 h) via K167/C47; C47M keeps 60 ± 5% activity and loses none after 16 h in 300 mM acetaldehyde. LIMK2 PROTAC THNAN69 has DC₅₀ = 1 nM (versus 33 nM for analogue 21b) and 10 nM depletes endogenous LIMK2 — proteomics/Western, not a simple UV chromatogram, carry that selectivity claim.
Evidence for the claim as stated.
Study at a glance
- Design
- Animal / in-vitro — Crystallography, 13C NMR, and a C47M mutant of E. coli DERA in concentrated acetaldehyde
- N
- Enzyme kinetics and structures rather than a biological sample N
- Population
- E. coli deoxyribose-phosphate aldolase and orthologues
- Outcome
- Crotonaldehyde covalently inactivates DERA via K167–C47; C47M retains activity in 300 mM acetaldehyde
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Why acetaldehyde kills the DERA aldolase
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
C47M loses no activity after 16 h in 300 mM acetaldehyde.
In contrast, the C47M mutant did not lose any activity even after 16 h in the presence of 300 mM acetaldehyde.
The variant retains 60 ± 5% of wild-type activity; Tm is 65.1 °C versus 66.6 °C for wild type.
Biochemical characterization of the new variant showed that it retains 60 ± 5% of the wildtype activity towards its natural substrate, and the melting temperature of 65.1 °C suggest a similar thermostability as found for wildtype DERA (66.6 °C).
Key findings
After 200–300 mM acetaldehyde the enzyme is irreversibly inactivated. Crotonaldehyde forms a Schiff base at K167 and a covalent link to C47. Crotonaldehyde inhibits more than 100-fold more potently than acetaldehyde (1 mM, <1 h). C47 is conserved in 91% of orthologues. C47M keeps 60 ± 5% activity and loses none after 16 h in 300 mM acetaldehyde.
Methodology
Authors combined crystallography, 13C NMR, and a C47M mutation to learn how E. coli DERA dies in concentrated acetaldehyde and how to protect it for synthesis.
Limitations
The work does not deliver a process-scale biocatalytic plant or map every aldehyde side product; only one protective mutation is fully characterized.
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