Cystine catabolism in mycelia of Microsporum gypseum, a dermatophytic fungus

Abstract

The fate of 35S label was studied during cystine degradation by mycelia of the dermatophytic fungus Microsporum gypseum. Excess free cystine in the medium was readily taken up and its sulfur moiety excreted as inorganic sulfate and sulfite. At intervals after 3-60 min of incubation with 35S cystine the products of cystine catabolism were extracted from the mycelia by boiling water and separated by thin layer chromatography and electrophoresis. A total of 10 sulfur-containing compounds were identified, and their relative radioactivity was assessed. After 3 min the mycelia contained, in addition to cystine, labeled cysteine and particularly cysteine sulfinic acid which was accompanied by a smaller amount of cysteic acid. Later on, oxidized and reduced glutathione, inorganic sulfate and taurine appeared consecutively. In all extracts, small amounts of labeled S-sulfocysteine were found, not, however, sulfite. The results suggest that the intermediates of cysteine degradation in the fungal mycelia are cysteine, cysteine sulfinate, unstable sulfinylpyruvate, sulfite and sulfate, i.e., that the catabolic pattern is similar to that of higher organisms. The formation and the role of S-sulfocysteine, cysteic acid, and of taurine is not yet completely understood, although certainly autoxidative processes are involved in the formation of the latter two compounds, and sulfitolysis in that of the former compound.

Secreted subtilisin gene family in Trichophyton rubrum

“…Therefore, the additional cleavage of these disulfide bonds by h-mercaptoethanol made keratin azure more accessible for Sub3 and Sub4. In vivo, as demonstrated with Microsporum gypseum, the cleavage of these disulfide bonds occurs by sulfitolyse following secretion of sulfites by the fungus (Kunert, 1982;Kunert and Truper, 1986). Sub3 and Sub4 specificity towards keratin azure (Fig.…”

Degradation of raw feather by a novel high molecular weight extracellular protease from newly isolated Bacillus cereus DCUW

“…Reports on feather degradation propose that keratinases act on disulfide bonds, which are responsible for the mechanical stability of keratin, thus making it easier for proteolytic enzymes to act. Other reports suggest that the reduction of disulfide bonds by disulfide reductase [4] or the production of sulfite and thiosulphate [20] to be involved in keratin degradation. Involvement of call-bound redox system for disulfide bond reduction has also been suggested in prokaryotes [4].…”

Novel treatment using thioglycolic acid for pincer nails

“…The method provides strong reduction and is indicated for thick pincer nails as well as nails that are too short. TGA acts by cleaving the disulfide bonds of the amino acid cystein in the nail protein molecule, thereby softening the nail . Once TGA has been applied, nails become soft and easy to bend or curve backward, whereas nails that have not been treated with TGA remain stiff and difficult to bend (Fig.…”