MICROSOMAL REDUCTIVE GLYCOSIDASE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 197  (3) , 681-686
Abstract
Rat liver microsomes contain a phenobarbital inducible, NADPH dependent, reductive glycosidase capable of cleaving several anthracycline antibiotics, including adriamycin and daunorubicin [cancer chemotherapeutic drugs], to deoxyaglycone products. The pH optimum for the reaction ranged from 7-7.4, and no metal requirements were noted. Molecular O reversibly inhibited the microsomal enzyme greater than 95% at 20% O2 partial pressure. CO, SKF 525A and sulfhydryl reagents were not inhibitory to the reaction, but the enzyme was sensitive to Cu++ and Zn++. Since the intact glycoside was necessary for conversion to the deoxyaglycone and a possible intermediate hydroxylated aglycone was not reduced to the deoxyaglycone, a concerted reaction mechanism was proposed. The reductive glycosidase activity was also present in rat brain, kidney and other tissues. Sensitivity of this enzyme to molecular O suggests a possible regulatory role for the enzyme in vivo.

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