Any amino acid carrying two amino groups.
| Member | Definition | Role |
|---|
| 2,3-diaminopropionic acid | A diamino acid that is alanine in which one of the hydrogens of the methyl group is replaced by an amino group. | 3-aminoalanine zwitterion; 3-aminoalanine |
| 2,4-diaminobutyric acid | A diamino acid that is butyric acid in which a hydrogen at position 2 and a hydrogen at position 4 are replaced by amino groups. | 2,4-diaminobutyric acid |
| beta-n-methylamino-l-alanine | A non-proteinogenic L-alpha-amino acid that is L-alanine in which one of the methyl hydrogens is replaced by a methylamino group. A non-proteinogenic amino acid produced by cyanobacteria, it is a neurotoxin that has been postulated as a possible cause of neurodegenerative disorders of aging such as Alzheimer's disease, amyotrophic lateral sclerosis, and the amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS-PDC) syndrome of Guam. | L-BMAA |
| endolysin | A diamino acid that is caproic (hexanoic) acid bearing two amino substituents at positions 2 and 6. | lysine |