Triacylglycerol lipase activity in baker's yeast (Saccharomyces cerevisiae).

An investigation of intracellular triacylglycerol lipase activity in baker's yeast (Saccharomyces cerevisiae) has been performed using emulsified triolein as substrate. Bovine serum has been used as emulsifier since it was found superior to gum arabic and albumin with respect to reproducibility of both triacylglycerol concentration in the assay mixture and specific lipase activity. No extracellular activity could be detected neither with whole cells nor with water or detergent "extracts" of intact cells as enzyme source. With disrupted cells the level of triacylglycerol lipase activity at a triacylglycerol concentration of 9.6 mM, at pH 7.5, and 30 degrees C was 190 mumol free fatty acids per h per g disrupted cells. Fractionation of a cytoplasmic extract of disrupted cells revealed that about 70% of the activity was associated with membrane fractions and 60% of this activity was present in the mitochondrial fraction. Purification of this fraction was followed by an increase in specific lipase activity which parallels the increase in specific activity of the cytochrome c oxidase.