| AS Family Member | Organism | Substrate | Biological Role |
|---|---|---|---|
| AMD2/YDR242W | *Saccharomyces cerevisiae* | Unknown (probable amide substrate[s]) | Probable amidase; exact physiological function remains uncharacterized, and wild-type *S. cerevisiae* does not grow on acetamide as sole nitrogen source, so its substrate cannot be assumed to be acetamide (pqac-00000007, pqac-00000008, pqac-00000035, pqac-00000036) |
| FAAH | Mammals | N-acylethanolamines (e.g., anandamide) | Endocannabinoid / fatty acid amide signaling termination by hydrolysis of NAEs (pqac-00000000, pqac-00000004, pqac-00000033) |
| AMI1 | *Arabidopsis thaliana* | Indole-3-acetamide | Auxin (IAA) biosynthesis via IAM hydrolysis (pqac-00000000, pqac-00000001, pqac-00000033) |
| amdS | *Aspergillus nidulans* | Acetamide | Nitrogen/carbon utilization from acetamide; classic fungal acetamidase used as a selectable marker (pqac-00000009, pqac-00000012, pqac-00000032) |
| MAE2 (Malonamidase E2) | *Bradyrhizobium japonicum* | Malonamate | Nitrogen metabolism in symbiosis; converts malonamate to malonate and ammonia (pqac-00000002, pqac-00000033) |
| Peptide amidase (PAM) | *Stenotrophomonas maltophilia* | C-terminal peptide amides | Peptide processing via selective hydrolysis of C-terminal amide bonds (pqac-00000002, pqac-00000033) |
| Aryl acylamidase (AAA) | Bacteria | Aryl acylamides | Likely detoxification / specialized amide hydrolysis; substrate pocket studies show AS-family structural adaptation for aromatic amides (pqac-00000002, pqac-00000034) |
| YlAMD1 | *Yarrowia lipolytica* | Acetamide | Nitrogen utilization; experimentally validated major acetamidase enabling growth on acetamide (pqac-00000011, pqac-00000012, pqac-00000017, pqac-00000018) |
| Note | AS family overview | Diverse amide-containing substrates | This comparison highlights the broad substrate range of amidase-signature enzymes; therefore, AMD2 sequence membership in the AS family does **not** by itself justify assigning acetamide as its native substrate (pqac-00000034, pqac-00000035, pqac-00000036, pqac-00000037) |


*Table: This table compares representative amidase signature family enzymes across taxa to show how widely their substrates and biological roles vary. It is useful for interpreting AMD2 cautiously: family membership supports amidase-like chemistry, but not a specific substrate such as acetamide.*