Biochemical characterization of chitin synthetase in yeast and mycelial forms of a dimorphic fungus, Candida albicans.

概要

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We obtained two cell forms of a dimorphic fungus, Candida albicans, the yeast-like (Y) and mycelial (M) forms, by growing them in Sabouraud's glucose medium and methionine containing medium, respectively. Spheroplasts were prepared from each cell type using a cell wall lytic enzyme (Zymolyase 100, 000) and then membrane fractions were isolated after hypotonic disruption. Membrane suspensions were fractionated by differential centrifugation under 160×g, 10, 000×g and 100, 000×g and the chitin synthetase activity in each fraction was determined. The 100, 000×g pellet fraction showed the highest activity, being enriched four-fold in the Y-form cells and five-fold in the M-form, as compared with the activity of total homogenate. With regard to enzyme activity-growth relationships, both forms of cells showed highest activity in the mid-logarithmic stage. Effects of divalent metal cations, pH, Km, heat stability and activators such as digitonin and several surfactants were investigated for chitin synthetase activity. No marked changes were observed in the biochemical properties of chitin synthetases between M and Y-forms, suggesting that the observed difference in their enzymic activity was due to the quantitative rather than the qualitative difference of chitin synthetase.
日本医真菌学会の論文