| Study (citation) | Publication date | Organism/species | Molecule(s) studied | Main finding relevant to function/structure/localization | Quantitative/statistical details | URL/DOI |
|---|---|---|---|---|---|---|
| Sim & Inoue, *Acta Crystallographica F* (pqac-00000000, pqac-00000002, pqac-00000003) | Jun 2023 | *Ramazzottius varieornatus* strain YOKOZUNA-1 | RvSOD15 (Cu/Zn SOD-like protein), V87H mutant | Established nearest-neighbor experimental evidence in the same species: Cu/Zn SOD-like protein adopts canonical Cu/Zn SOD fold and carries Cu and Zn, but an active-site His ligand is replaced by Val87; protein is also predicted to have an N-terminal signal peptide, suggesting secretion rather than classic cytosolic localization. | Catalyzed reaction discussed as 2 O2•− + 2 H+ → O2 + H2O2; crystal resolutions 2.20 Å (WT) and 2.10 Å (V87H); anomalous scattering confirmed Cu/Zn positions; sequence similarity reported as 44% to human SOD1 and 56% to a *Hypsibius exemplaris* Cu/Zn SOD. | https://doi.org/10.1107/S2053230X2300523X |
| Sim & Inoue, *Acta Crystallographica F* (pqac-00000001, pqac-00000007, pqac-00000008, pqac-00000009) | Jun 2023 | *Ramazzottius varieornatus* strain YOKOZUNA-1 | RvSOD15 and modeled RvSOD paralogs | Showed that some *R. varieornatus* Cu/Zn SOD paralogs are structurally atypical, with altered metal-binding residues, deletions in the electrostatic loop or β3 sheet, and likely reduced or lost canonical SOD activity; supports caution in assigning all tardigrade SOD paralogs as fully active enzymes. | Water interaction distances near Cu site 2.6–3.4 Å; V87H mutant still judged catalytically unsuitable; comparison cited to P104H BsSOD with activity ~10,000-fold lower than canonical Cu/Zn SODs; AlphaFold pLDDT examples: RvSOD15 86.99, RvSOD12 77.15, RvSOD16 var1 92.19; WT/V87H Rwork/Rfree 19.3/23.2 and 17.2/21.4. | https://doi.org/10.1107/S2053230X2300523X |
| Giovannini et al., *Life* (pqac-00000006) | May 2022 | *Paramacrobiotus spatialis* and *Acutuncus antarcticus* | Total SOD enzymatic activity during dehydration/rehydration | Provides tardigrade-level physiological evidence that SOD activity changes during anhydrobiosis, supporting antioxidant function in dehydration stress, though not specific to the A0A1D1UP68 protein. | In *P. spatialis*, no significant SOD differences among hydrated, dry, 1 h rehydrated, and 24 h rehydrated groups; in *A. antarcticus*, one-way ANOVA F(3,8) = 4.33, p < 0.05; dry animals had lower SOD activity than controls (t = 3.62, p < 0.05). | https://doi.org/10.3390/life12060817 |
| Nagwani et al., *Diversity* (pqac-00000004) | Aug 2022 | Tardigrades (review; includes *Ramazzottius varieornatus* context) | Antioxidant enzymes including SOD, CAT, GPx, GR | Review-level synthesis: SOD is part of endogenous ROS-detoxifying machinery implicated in successful anhydrobiosis; places Cu/Zn SOD-like proteins into the oxidative-stress pathway relevant to tardigrade survival and recovery. | Summarizes increased ROS with time in anhydrobiosis and notes reports that CAT/SOD activities are important in tardigrade anhydrobiosis; no protein-specific kinetic values for *R. varieornatus* Cu/Zn SOD given in the cited excerpt. | https://doi.org/10.3390/d14080664 |
| Sim & Inoue, *Acta Crystallographica F* (pqac-00000005) | Jun 2023 | *Ramazzottius varieornatus* strain YOKOZUNA-1 | RvSOD15 and other RvSOD family members | Concluded that tardigrades possess expanded antioxidant repertoires including SODs, but duplication does not imply equivalent enzyme function; some RvSOD members may be neofunctionalized or noncanonical. | No exact family count or expression fold-change reported in the excerpt; qualitative conclusion that some paralogs are truncated or mutated at catalytic residues. | https://doi.org/10.1107/S2053230X2300523X |


*Table: This table compiles the most relevant experimental and review evidence for functional annotation of *Ramazzottius varieornatus* Cu/Zn SOD-like proteins as proxies for UniProt A0A1D1UP68. It highlights what is directly known in tardigrades about reaction chemistry, structural constraints, likely localization, and stress-related roles.*