Lysosomal enzymes, also known as acid hydrolases, are responsible for degrading various biomolecules, including proteins, within the lysosomes of human cells. Lysosomes are membrane-bound organelles that function as the cellular recycling center, breaking down unwanted or damaged cellular components and foreign substances. The degradation process of proteins by lysosomal enzymes involves several steps:1. Targeting and delivery of proteins to lysosomes: Unwanted or damaged proteins are tagged with ubiquitin, a small protein that signals the need for degradation. These tagged proteins are then recognized by specific receptors and transported to the lysosome via vesicles, such as autophagosomes or endosomes.2. Acidification of the lysosomal lumen: The interior of the lysosome is maintained at an acidic pH around 4.5-5.0 by proton pumps V-ATPases present in the lysosomal membrane. This acidic environment is crucial for the optimal activity of lysosomal enzymes.3. Activation of lysosomal enzymes: Lysosomal enzymes are synthesized in the endoplasmic reticulum and transported to the Golgi apparatus, where they are modified and packaged into vesicles. These vesicles fuse with lysosomes, releasing the enzymes into the lysosomal lumen. Many lysosomal enzymes are synthesized as inactive precursors called proenzymes or zymogens, which are activated by proteolytic cleavage in the acidic environment of the lysosome.4. Protein degradation: Lysosomal enzymes, such as proteases, peptidases, and glycosidases, work together to break down proteins into their constituent amino acids and smaller peptides. Proteases cleave the peptide bonds between amino acids, while peptidases further break down the resulting peptides. Glycosidases remove any carbohydrate moieties that may be attached to the proteins.5. Recycling of degradation products: The amino acids and other small molecules generated from protein degradation are transported back into the cytosol, where they can be reused for the synthesis of new proteins or other cellular processes.In summary, lysosomal enzymes degrade proteins in human cells by targeting and delivering unwanted proteins to lysosomes, activating the enzymes in the acidic lysosomal environment, and breaking down the proteins into their constituent amino acids and smaller peptides, which can then be recycled by the cell.