Editing Melanin (section)

=== Other forms of melanins ===
Up until the 1960s, melanin was classified into eumelanin and pheomelanin. However, in 1955, a melanin associated with nerve cells was discovered, neuromelanin. In 1972 a water-soluble form, pyomelanin, was discovered. In 1976, allomelanin, the fifth form of the melanins, was found in nature.<ref name="Cao_2021" />

==== Peptidomelanin ====

[[File:A niger melanoliber.png|thumb|SEM micrograph of ''Aspergillus niger'' (strain: melanoliber) conodiophore possessing a large number of small conidospores (colorized). These spores release peptidomelanin into the surrounding medium during germination.]]

[[File:Peptidomelanin.jpg|thumb|The biochemical composition of peptidomelanin]]

Peptidomelanin is another water-soluble form of melanin.<ref>{{Cite journal |last1=Kolipakala |first1=Rakshita Sukruth |last2=Basu |first2=Suranjana |last3=Sarkar |first3=Senjuti |last4=Biju |first4=Beneta Merin |last5=Salazar |first5=Daniela |last6=Reddy |first6=Likhit |last7=Pradeep |first7=Pushya |last8=Yuvapriya |first8=Muniraj Krishnaveni |last9=Nath |first9=Shrijita |last10=Gall |first10=Riley |last11=Samprathi |first11=Anish Hemanth |last12=Balaji |first12=Harshitha |last13=Koundinya |first13=Eeshaan A. B. |last14=Shetye |first14=Aparna |last15=Nagarajan |first15=Deepesh |date=2024-08-07 |title=Fungal Peptidomelanin: A Novel Biopolymer for the Chelation of Heavy Metals |journal=ACS Omega |volume=9 |issue=34 |pages=36353–36370 |language=en |doi=10.1021/acsomega.4c03704 |pmid=39220543 |issn=2470-1343 |pmc=11359623}}</ref> It was found to be secreted into the surrounding medium by germinating ''[[Aspergillus niger]]'' (strain: melanoliber) spores. Peptidomelanin is formed as a copolymer between L-DOPA eumelanin and short [[peptide]]s that form a 'corona', that are responsible for the substance's solubility. The peptide chains are linked to the L-DOPA core polymer via peptide bonds. This lead to a proposed biosynthetic process involving the hydroxylation of tyrosinylated peptides formed via proteases during sporogenesis, which are then incorporated autoxidatively into a growing L-DOPA core polymer.

==== Selenomelanin ====
It is possible to enrich melanin with [[selenium]] instead of [[sulphur]]. This selenium analogue of pheomelanin has been successfully synthesized through chemical and biosynthetic routes using selenocystine as a feedstock.<ref>{{Cite journal |last1=Cao |first1=Wei |last2=McCallum |first2=Naneki C. |last3=Ni |first3=Qing Zhe |last4=Li |first4=Weiyao |last5=Boyce |first5=Hannah |last6=Mao |first6=Haochuan |last7=Zhou |first7=Xuhao |last8=Sun |first8=Hao |last9=Thompson |first9=Matthew P. |last10=Battistella |first10=Claudia |last11=Wasielewski |first11=Michael R. |last12=Dhinojwala |first12=Ali |last13=Shawkey |first13=Matthew D. |last14=Burkart |first14=Michael D. |last15=Wang |first15=Zheng |date=2020-07-22 |title=Selenomelanin: An Abiotic Selenium Analogue of Pheomelanin |url=https://pubs.acs.org/doi/10.1021/jacs.0c05573 |journal=Journal of the American Chemical Society |language=en |volume=142 |issue=29 |pages=12802–12810 |doi=10.1021/jacs.0c05573 |issn=0002-7863 |pmid=32638590 |s2cid=220413025 |access-date=30 August 2024 |archive-date=6 September 2023 |archive-url=https://web.archive.org/web/20230906193055/https://pubs.acs.org/doi/10.1021/jacs.0c05573 |url-status=live }}</ref> Due to selenium's higher atomic number, the obtained selenomelanin can be expected to provide better protection against ionising radiation as compared to the other known forms of melanin. This protection has been demonstrated with radiation experiments on human cells and bacteria, opening up the possibility of applications in space travel.<ref>{{Cite web |last=Mark Heiden |date=8 July 2020 |title=New biomaterial could shield against harmful radiation |url=https://news.northwestern.edu/stories/2020/07/new-biomaterial-could-shield-against-harmful-radiation-selenomelanin/ |access-date=29 January 2023 |publisher=Northwestern University |archive-date=30 August 2024 |archive-url=https://web.archive.org/web/20240830064612/https://news.northwestern.edu/stories/2020/07/new-biomaterial-could-shield-against-harmful-radiation-selenomelanin/ |url-status=live }}</ref>

==== Trichochromes ====
Trichochromes (formerly called trichosiderins) are pigments produced from the same [[metabolic pathway]] as the eumelanins and pheomelanins, but unlike those molecules they have low molecular weight. They occur in some red human hair.<ref>{{Cite journal |last1=Prota, G. |last2=Searle, A. G. |year=1978 |title=Biochemical sites of gene action for melanogenesis in mammals |url=http://www.gse-journal.org/10.1051/gse:19780101/pdf |journal=Annales de Génétique et de Sélection Animale |volume=10 |issue=1 |pages=1–8 |doi=10.1186/1297-9686-10-1-1 |pmc=2757330 |pmid=22896083 |doi-access=free |access-date=24 August 2019 |archive-date=30 August 2024 |archive-url=https://web.archive.org/web/20240830064741/http://www.gse-journal.org/10.1051/gse:19780101/pdf |url-status=live }}</ref>