| Property | SOD-2 summary | Evidence |
|---|---|---|
| Gene name | **sod-2**; historical synonym **sdm-1** | (pqac-00000000, pqac-00000003) |
| Protein name | **Manganese superoxide dismutase / mitochondrial superoxide dismutase (MnSOD)** | (pqac-00000000, pqac-00000001) |
| UniProt accession | **P31161** | (pqac-00000000) |
| Organism | **Caenorhabditis elegans** | (pqac-00000000, pqac-00000003) |
| Enzyme class | **Superoxide dismutase, EC 1.15.1.1** | (pqac-00000001, pqac-00000003) |
| Catalytic reaction | Catalyzes dismutation of **superoxide anion (O2•−)** to **hydrogen peroxide (H2O2)** and **oxygen (O2)** | (pqac-00000001, pqac-00000016) |
| Physiologic substrate specificity | Primary substrate is **superoxide radical** generated in mitochondria; product H2O2 can serve signaling roles | (pqac-00000008, pqac-00000015, pqac-00000018) |
| Metal cofactor | **Manganese (Mn)** | (pqac-00000000, pqac-00000001) |
| Molecular mass, monomer | **21,986 Da**, 192 aa mature protein | (pqac-00000000, pqac-00000002) |
| Oligomeric state / dimer mass | Functions as an **active dimer**; measured mass **44,961 Da** | (pqac-00000000, pqac-00000002) |
| Specific activity | **2516 units/mg protein** when expressed in *E. coli* | (pqac-00000000) |
| Subcellular localization | **Mitochondrial**, specifically consistent with the **mitochondrial matrix** | (pqac-00000005, pqac-00000008) |
| N-terminal transit peptide | Contains an **N-terminal mitochondrial transit peptide**; mature enzyme generated after targeting/processing | (pqac-00000001, pqac-00000005, pqac-00000006) |
| Physical mitochondrial association | Reported as physically associated with the **I:III:IV respiratory supercomplex** in the inner mitochondrial membrane context | (pqac-00000024, pqac-00000031) |
| Isoelectric point (pI) | **6.5** | (pqac-00000000) |
| Chromosome location | **Chromosome I** | (pqac-00000001) |
| Key domains / family | Member of the **iron/manganese superoxide dismutase family**; Mn/Fe SOD-type enzyme | (pqac-00000000, pqac-00000001) |
| Inhibitor sensitivity | **Not inhibited by hydrogen peroxide or potassium cyanide**, consistent with MnSOD rather than Cu/ZnSOD | (pqac-00000000, pqac-00000001) |
| Functional complementation | Expressed SOD-2 protects **SOD-deficient *E. coli*** from methyl viologen-induced oxidative stress | (pqac-00000001) |
| Core biological role in worm | Major mitochondrial superoxide detox enzyme; also shapes redox signaling by controlling conversion of mitochondrial superoxide into signaling-competent peroxide | (pqac-00000008, pqac-00000018, pqac-00000029) |
| Lifespan phenotype of loss | **Deletion of sod-2 extends lifespan** in *C. elegans* despite increased oxidative stress sensitivity and oxidative damage | (pqac-00000007, pqac-00000012, pqac-00000014) |
| Mitochondrial-function phenotype of loss | sod-2 mutants show **decreased oxygen consumption**, slow development, low brood size, and slow defecation, resembling long-lived mitochondrial mutants | (pqac-00000007, pqac-00000009, pqac-00000010) |
| Interaction with mitochondrial mutants | **Extends lifespan in clk-1**, but **shortens lifespan in isp-1** backgrounds; supports a mitochondrial threshold model | (pqac-00000011, pqac-00000032, pqac-00000033) |
| Role in ROS signaling | Loss of SOD-2 elevates mitochondrial superoxide; longevity signaling requires downstream conversion involving **SOD-1** and **LET-60/RAS** redox signaling | (pqac-00000018, pqac-00000027) |
| Role in reproduction | SOD-2-generated **H2O2 activates sperm pseudopod extension** and is required for normal sperm activation | (pqac-00000015, pqac-00000016) |
| Comparison with SOD-3: localization/class | Both **SOD-2 and SOD-3 are mitochondrial MnSODs** with transit peptides and comparable specific activities | (pqac-00000001, pqac-00000043) |
| Comparison with SOD-3: biochemical differences | Both are dimers and active MnSODs, but show **different electrophoretic mobilities and isoelectric points** | (pqac-00000001) |
| Comparison with SOD-3: expression/regulation | **sod-2** is relatively constitutive and similar in adult/dauer, whereas **sod-3** is more **dauer-associated** and strongly induced in **daf-2** mutants; sod-2 is more linked to **SKN-1/p38 MAPK** regulation, sod-3 to **DAF-16/IIS** | (pqac-00000022, pqac-00000042, pqac-00000044, pqac-00000045) |


*Table: This table summarizes the main biochemical, localization, and functional properties of C. elegans SOD-2, including direct comparisons with the paralog SOD-3. It is useful as a compact reference for annotation of sod-2/MnSOD in mitochondrial redox biology and lifespan signaling.*