Fungal melanins differ in planar stacking distances

Arturo Casadevall, Antonio Nakouzi, Pier R. Crippa, Melvin Eisner

Research output: Contribution to journalArticle

Abstract

Melanins are notoriously difficult to study because they are amorphous, insoluble and often associated with other biological materials. Consequently, there is a dearth of structural techniques to study this enigmatic pigment. Current models of melanin structure envision the stacking of planar structures. X ray diffraction has historically been used to deduce stacking parameters. In this study we used X ray diffraction to analyze melanins derived from Cryptococcus neoformans, Aspergillus niger, Wangiella dermatitides and Coprinus comatus. Analysis of melanin in melanized C. neoformans encapsulated cells was precluded by the fortuitous finding that the capsular polysaccharide had a diffraction spectrum that was similar to that of isolated melanin. The capsular polysaccharide spectrum was dominated by a broad non-Bragg feature consistent with origin from a repeating structural motif that may arise from inter-molecular interactions and/or possibly gel organization. Hence, we isolated melanin from each fungal species and compared diffraction parameters. The results show that the inferred stacking distances of fungal melanins differ from that reported for synthetic melanin and neuromelanin, occupying intermediate position between these other melanins. These results suggest that all melanins have a fundamental diffracting unit composed of planar graphitic assemblies that can differ in stacking distance. The stacking peak appears to be a distinguishing universal feature of melanins that may be of use in characterizing these enigmatic pigments.

Original languageEnglish (US)
Article numbere30299
JournalPLoS One
Volume7
Issue number2
DOIs
StatePublished - Feb 16 2012
Externally publishedYes

Fingerprint

Melanins
melanin
Cryptococcus neoformans
Pigments
X-ray diffraction
X-Ray Diffraction
Polysaccharides
Coprinus comatus
polysaccharides
Exophiala
Diffraction
Coprinus
pigments
Dermatitis
X ray diffraction
Molecular interactions
Aspergillus niger
Aspergillus
dermatitis
Biological materials

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Fungal melanins differ in planar stacking distances. / Casadevall, Arturo; Nakouzi, Antonio; Crippa, Pier R.; Eisner, Melvin.

In: PLoS One, Vol. 7, No. 2, e30299, 16.02.2012.

Research output: Contribution to journalArticle

Casadevall, Arturo ; Nakouzi, Antonio ; Crippa, Pier R. ; Eisner, Melvin. / Fungal melanins differ in planar stacking distances. In: PLoS One. 2012 ; Vol. 7, No. 2.
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