Chitin synthase activity and the rate of chitin formation in cell‐division cycle mutant Saccharomyces cerevisiae cdc 24

At the nonpermissive temperature (37 degrees C) the cells of the temperature-sensitive mutant Saccharomyces cerevisiae cdc 24 accumulated chitin 10 times faster than at 22 degrees C. In situ determinations of the activity of chitin synthase revealed that in the cells grown at 37 degrees C more than 37% of the total chitin synthase were in the active state whereas in cells grown at 22 degrees C only 7% of the potential enzyme activity were expressed. When the enzyme activity was calculated per cell number unit, there was 10 times more of the active chitin synthase per cell in the cells grown at 37 degrees C than in the cells grown at 22 degrees C, a value which correlated well with the observed difference in the rates of chitin accumulation at different temperatures.