Abstract
Both human and f MPS VI result from deficient ASB activity (∼ 6% of normal) and accumulation of dermatan sulfate (DS). Normal human, normal f and f MPS VI hepatic ASB were purified (spec. act. 55, 106, 2.7 umol/h/mg prot., resp.) and molecular weights (MW) were determined by PAGE (∼ 80,000, 160,000, 78,000, resp.) and Sephadex G-200 chromatography (∼ 45,000, 110,000, 53,000, resp.). These data were consistent with human ASB and rASB being monomers and the normal f ASB a dimer. When the rASB was incubated with 1 mM DTT, the MW was 160,000 (PAGE) and 100,000 (Sephadex), suggesting that DTT caused dimerization of the rASB. The DTT-treated purified rASB was increased 5-fold and had markedly increased cryostability. Normal f and f MPS VI buffered whole bloods were incubated ± 10 mM DTT, leukocytes isolated, ASA and ASB separated by DEAE-cellulose chromatography, and DS determined by cellogel electrophoresis. The WBC rASB activity was increased 6-fold with DTT (spec. act. 0.025 → 0.164) and the DS was markedly decreased (0.37→ < 0.02 ug/ug prot.); DTT had no effect on ASA, normal ASB, or normal DS levels. These findings suggest that the mutation in f MPS VI may involve a cysteine residue which hinders dimerization and that -SH reduction results in dimerization with enhanced rASB activity. Thiol-induced subunit association provides a novel approach for enzyme manipulation therapy which can be tested in vivo using the animal model.
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Vine, D., Mcgovern, M., Schuchman, E. et al. 768 ENZYME MANIPULATION: ENHANCEMENT OF THE RESIDUAL ARYLSULFATASE B (rASB) ACTIVITY IN FELINE (f) MUCO-POLYSACCHARIDOSIS (MPS) VI BY DTT. Pediatr Res 15 (Suppl 4), 570 (1981). https://doi.org/10.1203/00006450-198104001-00792
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DOI: https://doi.org/10.1203/00006450-198104001-00792