0000000000239872
AUTHOR
Francisco Dubón
Studies on zymogenicity and solubilization of chitin synthase from Candida albicans
The zymogenic form of the chitin synthase present in mixed membrane preparations was extracted by digitonin treatment. The residual extracted membranes exclusively retained the basal activity. Trypsin activation of the zymogenic form of the enzyme did not modify the digitonin solubilization characteristics of the original zymogenic form, suggesting significant differences between ‘in vivo’ activation of chitin synthase and that carried out by trypsin ‘in vitro’.
Evidence for the involvement of acylglycerides on chitin synthetase activity inCandida albicans
The effect of a lipase activity (EC 3.1.1.3) on the chitin synthetase from Candida albicans has been studied, both on the active and the trypsin activated enzyme. Removal of fatty acids from acylglycerides by lipase has an inhibitory effect on the activity as well as on the ‘in vitro’ activation process by trypsin in the membrane-bound enzyme and in the chitosomes. This would indicate that an adequate lipid environment is required for both the activation process and proper function of the synthetase activity.
Chitin synthetase activity in Candida albicans: subcellular distribution in yeast cells and protoplasts
Chitin synthetase activity was detected in a partly zymogenic form in cell-free homogenates obtained from C. albicans yeast cells and protoplasts of the same type of cells. By isopycnic centrifugation on sucrose gradients of the cell-free homogenates two fractions with chitin synthetase activity were obtained: one was associated with the plasma membrane (labelled with [ 3 H]concanavalin A (con A) and buoyant density 1·195 g ml −1 ) in a partly active state, and the second was in the cytoplasm, where the enzyme was in a particulate fully zymogenic form, lacking affinity to con A. The buoyant density of the enzyme found in this location depended on the method of cell breakage. Lysis of partly…
Effect of digitonin on membrane-bound and chitosomal chitin synthetase activity in protoplasts from yeast cells ofCandida albicans
The effect of digitonin on chitin synthetase present in membrane (MMF) and cytoplasmic fractions (chitosomes) (CF) from C. albicans yeast protoplasts has been determined. The zymogen is preferentially, but not exclusively, solubilized by digitonin from MMF. Centrifugation of distinct solubilized preparations, containing either zymogen, in vivo active enzyme and/or trypsin activated enzyme, on linear sucrose gradients suggests that both zymogen and trypsin activated enzyme sediment slightly slower than the active enzyme, pointing out differences between the activation processes in vivo and in vitro or, alternatively, that both enzyme activities (active in vivo and zymogenic) correspond to di…