Composition and activity of commercial triacylglycerol acylhydrolase preparations

Commercial lipase preparations were surveyed to determine gross composition, amounts of nonprotein impurities, and esterolytic and lipolytic activities. Most of the 34 commercial lipase preparations contained more than 80% nonproteinaceous material, with salt and carbohydrate being the most abundant materials. The tributyrin hydrolase activity of these commercial lipase preparations was determined and expressed as lipase/esterase forestomach units (LFU). Tributyrin hydrolase activity ranged from negligible (5.3 LFU/g) to very high (>1,000,000 LFU/g). Aspergillus and Penicillium preparations were low in tributyrin hydrolase activity. Candida rugosa preparations were intermediate in activity. Preparations of porcine pancreas, Rhizomucor, Pseudomonas, and Rhizopus lipases exhibited a broad range of levels of activity. No relation between protein content and tributyrin hydrolase activity was observed. Isoelectric focusing of the proteins present in the preparations demonstrated the presence of between 2 and 27 isophoretically discrete bands in the isoelectric range of 3 to 9. Although there were many similarities of distribution of protein isoelectric points within genera and species, the preparations generally displayed unique patterns of isophoretically discrete protein bands. Lipase zymography demonstrated the presence of 0 to 7 isophoretically discrete lipase activities in each preparation, spanning the entire range of isoelectric points surveyed.