Characterization of Fonsecaea pedrosoi melanin.
The constituents of the melanin complex from mycelial forms of Fonsecaea pedrosoi were partially characterized. The pigment was mainly accumulated on large alkali-extractable, electron-dense cytoplasmic bodies (melanosomes) and, apparently, on the outer layer of the cell wall as external deposits within verrucose outgrowths. Using electron microscopy and Thiéry's periodate/thiosemicarbazide/silver proteinate staining method, glycogen-like particles were also detected at the periphery of the cells. Melanin constituents comprised aromatic and aliphatic/glycosidic structures with a predominance of the latter. Infrared spectra showed the presence of hydroxyl, carbonyl and carboxyl groups. The aliphatic/glycosidic moiety consisted of fatty acids and polysaccharides with protein, in a ratio protein/polysaccharide 1:15. Rhamnose, mannose, galactose and glucose (in the ratio 1:2:4:3.5) were the constituents of the polysaccharide. Lipid components included even-numbered, saturated and unsaturated fatty acids (in the ratio 2:1) ranging from C16 to C18. Palmitic and oleic acids were the prominent fatty acids. Aspartic and glutamic acids, leucine, glycine and alanine were the major amino acids. Non-pigmented cells of F. pedrosoi were studied for comparison with the pigmented forms: they did not accumulate acid-insoluble precursors of melanin.
Alviano
C S
CS
Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Ilha, do Fundão, Brazil.
Farbiarz
S R
SR
De Souza
W
W
Angluster
J
J
Travassos
L R
LR
D000596:Amino Acids / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D002862:Chromoblastomycosis / Q000382:microbiology*; D005227:Fatty Acids / Q000032:analysis; D006801:Humans; D008543:Melanins / Q000737:chemistry / Q000378:metabolism*; D008854:Microscopy, Electron; D003904:Mitosporic Fungi / Q000378:metabolism* / Q000648:ultrastructure; D013055:Spectrophotometry, Infrared
D000596:Amino Acids; D002241:Carbohydrates; D005227:Fatty Acids; D008543:Melanins