What do lipases catalyze the hydrolysis of?

Lipases are enzymes specifically designed to catalyze the hydrolysis of fats and carboxylic esters. These enzymes play a crucial role in lipid metabolism by breaking down triglycerides (the main constituents of body fat in humans and other animals, as well as vegetable fat). During this hydrolysis process, lipases cleave the ester bonds in triglycerides, converting them into glycerol and free fatty acids.

The specificity of lipases allows them to act efficiently on different types of lipids, including dietary fats, thereby facilitating the digestion and absorption of lipids in the gastrointestinal tract. This enzymatic action is essential for proper nutrient assimilation and energy production in the body.

While enzymes do exist for proteins (proteases) and carbohydrates (amylases), these are not the function of lipases. Nucleic acids are hydrolyzed by nucleases. Therefore, the characteristic action of lipases on fats and carboxylic esters confirms that option D is the correct answer.