Abstract
Late infantile MLD is a familial degenerative neurologic disease presumably caused by a mutation of arylsulfatase A (ASA). In order to study the residual arylsulfatase activity in MLD, the two lysosomal isoenzymes, ASA and ASB, were purified from human liver and a specific antiserum to ASA prepared. The IgG fraction of the antiserum was covalently bound to CNBr-activated Sepharose 4B. Liver homogenates from normal and MLD patients as well as purified ASA gave an identical precipitin line when examined by double gel diffusion. The ASA activity of the preparations was determined and were then adsorbed with the insoluble anti-ASA antibodies. After adsorption, no crossreacting material with anti-ASA antiserum could be demonstrated. The ASA activity after adsorption was 17% of the original for the normal liver homogenate, 9% for the purified ASA, and 98.5% for the MLD liver homogenate. When purified normal ASA and ASB activities were determined, the ASB was found to have residual enzymatic activity (7%) in the A substrate determining assay. A synergistic effect of the normal and mutant ASA on the ASB activity determination assay was also observed. These data indicate that the mutant ASA in late infantile MLD has no enzymatic activity and the residual “A-like” activity is secondary to the ASB isoenzyme. Further studies are needed to determine whether or not the B isoenzyme in this form of MLD is enzymatically and antigenically identical to the normal B.
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Shapira, E., Nadler, H. THE NATURE OF RESIDUAL ARYLSULFATASE ACTIVITY IN LATE INFANTILE METACHROMATIC LEUKODYSTROPHY (MLD). Pediatr Res 8, 395 (1974). https://doi.org/10.1203/00006450-197404000-00333
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DOI: https://doi.org/10.1203/00006450-197404000-00333