Selenomelanin: An Abiotic Selenium Analogue of Pheomelanin

• DOI: 10.1021/jacs.0c05573
• Publication Date: 2020-07-08T12:00:31Z
• Authors: Wei Cao; Naneki C. McCallum; Qing Zhe Ni; Weiyao Li; Hannah Boyce; Haochuan Mao; Xuhao Zhou; Hao Sun; Matthew P. Thompson; Claudia Battistella; Michael R. Wasiel...; Ali Dhinojwala; Matthew D. Shawkey; Michael D. Burkart; Zheng Wang; Nathan C. Gianneschi
• Keywords: Selenocysteine

Melanins are a family of heterogeneous biopolymers found ubiquitously across plant, animal, bacterial, and fungal kingdoms where they act variously as pigments radiation protection agents. There exist five multifunctional yet structurally biosynthetically incompletely understood varieties melanin: eumelanin, neuromelanin, pyomelanin, allomelanin, pheomelanin. Although eumelanin allomelanin have been the focus most studies to date, some research suggests that pheomelanin has better absorption coefficient for X-rays than eumelanin. We reasoned if selenium enriched melanin existed, it would be X-ray protector sulfur-containing because is proportional fourth power atomic number (Z). Notably, an essential micronutrient, with amino acid selenocysteine being genetically encoded in 25 natural human proteins. Therefore, we hypothesize selenomelanin exists nature, provides superior ionizing organisms compared known melanins. Here introduce this novel analogue through chemical biosynthetic routes using selenocystine feedstock. The resulting structural mimic effectively prevented neonatal epidermal keratinocytes (NHEK) from G2/M phase arrest under high-dose irradiation. Provocatively, beneficial role points sixth variety discovered melanin.