Iduronidase (EC 3.2.1.76, L-iduronidase, alpha-L-iduronidase, laronidase), sold as Aldurazyme, is an enzyme with the systematic name glycosaminoglycan alpha-L-iduronohydrolase. This enzyme catalyses the hydrolysis of unsulfated alpha-L-iduronosidic linkages in dermatan sulfate.It is a glycoprotein enzyme found in the lysosomes of cells. It is involved in the degeneration of glycosaminoglycans such as dermatan sulfate and heparan sulfate. The enzyme acts by hydrolyzing the terminal alpha-L-induronic acid residues of these molecules, degrading them. The protein is reported as having a mass of approximately 83 kilodaltons.