Asparagine, glutamine and lysine are proteinaceous diamino acids which are components of proteins. These three diamino acids are coded by codons of the genetic material and belong therefore to the cationic amino acids.
In biochemistry, diamino acids are of particular interest. Diamino acids are used for the synthesis of specific peptide nucleic acids, such as daPNA. Artificial peptide nucleic acids are capable of forming duplex structures with individual DNA- and RNA-strands and are, therefore, not only called DNA-analog, but also they are considered as candidates for the first genetic material on Earth. The corresponding diamino acids such as 2,3-diaminopropanoic acid were detected in the Murchison meteorite  and in a simulated comet.
References and notes
- Egholm, M; Buchardt, O; Christensen, L; Behrens, C; Freier, SM; Driver, DA; Berg, RH; Kim, SK; Norden, B; Nielsen, PW (1993). "PNA hybridizes to complementary oligonucleotides obeying the Watson-Crick hydrogen bonding rules". Nature. 365 (6446): 566–568. Bibcode:1993Natur.365..566E. PMID 7692304. doi:10.1038/365566a0.
- Meierhenrich, UJ; Munoz Caro, GM; Bredehöft, JH; Jessberger, EK; Thiemann, WHP (2004). "Identification of diamino acids in the Murchison meteorite". PNAS. 101 (25): 9182–9186. Bibcode:2004PNAS..101.9182M. PMC . PMID 15194825. doi:10.1073/pnas.0403043101.
- Munoz Caro, GM; Meierhenrich, UJ; Schutte, WA; Barbier, B; Arcones Segovia, A; Rosenbauer, H; Thiemann, W; Brack, A; Greenberg, JM (2002). "Amino acids from ultraviolet irradiation of interstellar ice analogues". Nature. 416 (6879): 403–406. Bibcode:2002Natur.416..403M. PMID 11919624. doi:10.1038/416403a.