BIOCHEMICAL GENETIC STUDIES OF THE FELINE MODEL OF HUMAN MUCOPOLYSACCHARIDOSIS VI, MAROTEAUX-LAMY DISEASE.
Item
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Title
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BIOCHEMICAL GENETIC STUDIES OF THE FELINE MODEL OF HUMAN MUCOPOLYSACCHARIDOSIS VI, MAROTEAUX-LAMY DISEASE.
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Identifier
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AAI8222964
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identifier
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8222964
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Creator
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MCGOVERN, MARGARET MARY.
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Contributor
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Robert J. Desnick
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Genetics
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Abstract
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The enzymatic defect in feline mucopolysaccharidosis VI (MPS VI) was characterized and therapeutic strategies evaluated. A method was developed for the detection of heterozygotes for feline and human MPS VI. Arylsulfatase A (ASA) and B (ASB) activities were assayed in leukocyte extracts following separation of the enzymes by batch chromatography. ASB specific activities did not permit heterozygote identification, whereas the ASB to ASA activity ratio discriminated all 16 obligate heterozygotes for the feline and human disorders.;Normal feline and human hepatic ABS isozymes were purified to homogeneity with final specific activities of 1,100 and 800 umoles/h/mg protein, respectively. Both enzymes had the same pH optimum, however, the feline ASB was more electronegative, had a lower K(,m) and pI and was more thermostable. The molecular weight of the feline enzyme was twice that of human ASB by gel filtration, analytical polyacrylamide gel electrophoresis, and sucrose density-gradient centrifugation. SDS gel electrophoresis revealed a single protein band for each enzyme, and alkylation and cross linking studies were consistent with the feline enzyme being a homodimer and the human isozyme a monomer.;Hepatic ASB from normal and MPS VI cats was purified over 2,800- and 1,800-fold, respectively. The MPS VI residual activity had a higher K(,m), an altered electrophoretic mobility, half the native molecular weight, decreased stability, and was a monomer. When incubated with sulfhydryl reagents, the residual activity was enhanced, whereas the normal enzyme was unaffected. In the presence of dithiothreitol (DTT) or cysteamine, the residual activity had a molecular weight similar to that of the normal enzyme, suggesting that the monomeric residual enzyme was dimerized in the presence of thiol-reducing agents. When 2 mM DTT or cysteamine was incubated with whole blood from an MPS VI cat, the leukocyte residual ASB activity was increased 11- and 20-fold, respectively, and the accumulated dermatan sulfate degraded. Intravenous administration of DTT effected transient increase in leukocyte activity, but no decrease in substrate levels. In contrast, administration of cysteamine increased leukocyte residual activity more than 6-fold 30 min post-infusion, and decreased substrate to 35 percent of the initial level and remained at about 45% of pre-infusion values during the 120 min period studied.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
