Microbodies from rat liver and a variety of plant tissues were osmotically shocked and subsequently centrifuged at 40,000 g for 30 min to yield supernatant and pellet fractions. From rat liver microbodies, all of the uricase activity but little glycolate oxidase or catalase activity were recovered in the pellet, which probably contained the crystalline cores as many other reports had shown. All the measured enzymes in spinach leaf microbodies were solubilized. With microbodies from potato tuber, further sucrose gradient centrifugation of the pellet yielded a fraction at density 1.28 g/cm3 which, presumably representing the crystalline cores, contained 7% of the total catalase activity but no uricase or glycolate oxidase activity. Using microbodies from castor bean endosperm (glyoxysomes), 50–60% of the malate dehydrogenase, fatty acyl CoA dehydrogenase, and crotonase and 90% of the malate synthetase and citrate synthetase were recovered in the pellet, which also contained 96% of the radioactivity when lecithin in the glyoxysomal membrane had been labeled by previous treatment of the tissue with [14C]choline. When the labeled pellet was centrifuged to equilibrium on a sucrose gradient, all the radioactivity, protein, and enzyme activities were recovered together at peak density 1.21–1.22 g/cm3, whereas the original glyoxysomes appeared at density 1.24 g/cm3. Electron microscopy showed that the fraction at 1.21–1.22 g/cm3 was comprised of intact glyoxysomal membranes. All of the membrane-bound enzymes were stripped off with 0.15 M KCl, leaving the "ghosts" still intact as revealed by electron microscopy and sucrose gradient centrifugation. It is concluded that the crystalline cores of plant microbodies contain no uricase and are not particularly enriched with catalase. Some of the enzymes in glyoxysomes are associated with the membranes and this probably has functional significance.
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1 August 1973
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August 01 1973
LOCALIZATION OF ENZYMES WITHIN MICROBODIES
A. H. C. Huang,
A. H. C. Huang
From the Thimann Laboratories, University of California, Santa Cruz, California 95060
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H. Beevers
H. Beevers
From the Thimann Laboratories, University of California, Santa Cruz, California 95060
Search for other works by this author on:
A. H. C. Huang
From the Thimann Laboratories, University of California, Santa Cruz, California 95060
H. Beevers
From the Thimann Laboratories, University of California, Santa Cruz, California 95060
Received:
March 15 1973
Revision Received:
April 30 1973
Online ISSN: 1540-8140
Print ISSN: 0021-9525
Copyright © 1973 by The Rockefeller University Press
1973
J Cell Biol (1973) 58 (2): 379–389.
Article history
Received:
March 15 1973
Revision Received:
April 30 1973
Citation
A. H. C. Huang, H. Beevers; LOCALIZATION OF ENZYMES WITHIN MICROBODIES . J Cell Biol 1 August 1973; 58 (2): 379–389. doi: https://doi.org/10.1083/jcb.58.2.379
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