Subellular distribution of S-adenosylamenthionine decarboxylase in rat liver. Evidence of decarboxylation of S-adenosylmenthionine separate from synthesis of spermidine |
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| Authors: | John A. Sturman |
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| Affiliation: | 1. Department of Pediatric Research, Institute for Basic Research in Mental Retardation, Staten Island, N.Y,, U.S.A.;2. Department of Pediatrics and Clinical Genetics Center, Mount Sinai School of Medicine of the City University of New York, N.Y., U.S.A. |
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| Abstract: | The acitivity of S-adenosylmethionine decarboxylase in rat liver homogenates is localized chiefly in the crude nuclear fraction, probably associated with membrane fragments, with the remainder in the supernatant fraction. This distribution is not paralleled by the activity of the cytoplasmic enzyme, lactate dehydrogenase. The spermidine-synthesizing activity of whole homogenate is recovered entirely in the supernatant fraction. Measurement of various kinetic parameters in crude fractions provided no positive evidence for isozymes of S-adenosylmethionine decarboxylase. Some species do not possess a sedimentable fraction of S-adenosylmethionine decarboxylase activity in liver. In those species all activity present in the whole homogenate of liver is released into the supernatant fraction. |
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