Pathogenic roles of extracellular proteinases from fungi are of great interest in human mycoses. In this article, our recent studies on the properties of isolated or purified extracellular proteinases of various fungi and their relationship with pathogenecity were reviewed.
(1)
Candida albicans produced and released a carboxyl proteinase (CAPP) with pH optima 4.0 and
Mr 42, 000. Its production was induced in the culture medium containing human stratum corneum as a nitrogen source. Cell growth was suppressed by the addition of a specific inhibitor (pepstatin). These results suggested the pathogenic roles of cell invasion and growth in candidiasis.
(2)
Sporothrix schenckii produced two proteinases; proteinase I: pH optima 6.0,
Mr 36, 500, serine proteinase, and proteinase II; pH optima 3.5,
Mr 39, 000, carboxyl proteinase. Proteinases I and II, each other, urged cell growth compensatively both in vitro and in vivo. Topical application of proteinase inhibitors (pepstatin and chymostatin) was found to be therapeutic for the cutaneous sporotrichosis.
(3) Some properties of a proteinase from
Hendersonula toluroidea (pH optima 9.0,
Mr 34, 000, serine proteinase) and acid serine proteinasis from
Trichophyton mentagrophytes et
rubrum were also described. It is of interest that acid and alkaline proteinasis from
T. rubrum were produced extracellularly in the different time of culture. Proteinase activity as a pathogenic factor may explain
T. rubrum granuloma and different clinical manifestations by
Nocardia asteroides et brasiliensis. Enzyme activity of
T. rubrum isolated from granuloma was higher than that from superficial infection. In addition, enzyme activity of
N. brasiliensis was higher than that of
N. asteroides which is thought to be less pathogenic. On the other hand, a strain of
N. asteroides presenting strongly pathogenic clinical features produced higher proteinase activity.
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