Cytosolic hydrolase degradation

Glycosaminoglycans are degraded in lysosomes, which contain hydrolytic enzymes that are most active at a pH of approximately 5. [Note Therefore, as a group, these enzymes are called acid hydrolases.] The low pH optimum is a protective mechanism that prevents the enzymes from destroying the cell should leakage occur into the cytosol where the pH is neutral. With the exception of keratan sui-... 

The action of 26S proteasome generates several types of products including free peptides, and peptides linked to ubiquitin chains, which are converted to free and reusable Ub by the action of ubiquitin-C-terminal hydrolases or isopeptidases. Cytosolic peptidases further degrade short peptides to free amino acids. 

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