Selenomelanin: An Abiotic Selenium Analogue of Pheomelanin

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. Wasielewski, Ali Dhinojwala, Matthew D. Shawkey, Michael D. Burkart, Zheng Wang, Nathan C. Gianneschi

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

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

Original languageEnglish
Pages (from-to)12802-12810
Number of pages9
JournalJournal of the American Chemical Society
Volume142
Issue number29
DOIs
Publication statusPublished - Jul 22 2020

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Cao, W., McCallum, N. C., Ni, Q. Z., Li, W., Boyce, H., Mao, H., Zhou, X., Sun, H., Thompson, M. P., Battistella, C., Wasielewski, M. R., Dhinojwala, A., Shawkey, M. D., Burkart, M. D., Wang, Z., & Gianneschi, N. C. (2020). Selenomelanin: An Abiotic Selenium Analogue of Pheomelanin. Journal of the American Chemical Society, 142(29), 12802-12810. https://doi.org/10.1021/jacs.0c05573