Iduronate-2-sulfatase substrates (IDS substrates)

Iduronate-2-sulfatase substrates are glycosaminoglycans (GAGs), primarily dermatan sulfate and heparan sulfate, which are essential components of the extracellular matrix and cell surface (UniProt P22304). These complex carbohydrates play vital roles in cell signaling, tissue repair, and structural support (PubChem). In a healthy physiological state, these molecules are continuously synthesized and subsequently degraded within lysosomes by a series of enzymes, including iduronate-2-sulfatase (IDS) (NIH GARD). A deficiency in IDS leads to Mucopolysaccharidosis type II (Hunter syndrome), characterized by the pathological accumulation of these substrates in nearly all organs, causing progressive physical and cognitive impairment (Muenzer et al., 2017). Therapeutic interventions like enzyme replacement therapy (ERT) utilize recombinant IDS to catalyze the breakdown of these accumulated GAGs (FDA: Elaprase). Drugs such as idursulfase and idursulfase beta are designed to replace the missing enzyme, thereby facilitating the clearance of these substrates from the lysosomes of affected cells. Newer therapies, such as pabinafusp alfa, are engineered to cross the blood-brain barrier to address the accumulation of these substrates in the central nervous system (JCR Pharmaceuticals). Monitoring the levels of these substrates in urine or blood serves as a critical biomarker for diagnosing the disease and evaluating the efficacy of treatment (StatPearls: Hunter Syndrome).

Other names

Dermatan sulfateHeparan sulfateGlycosaminoglycansGAGsMucopolysaccharides

Enzyme replacement therapy (ERT) provides exogenous iduronate-2-sulfatase to catalyze the hydrolysis of 2-sulfate groups from these substrates, enabling their subsequent degradation and clearance from lysosomes (FDA: Elaprase).