This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Heupel, R. Articles by Heldt, H. W. Search for Related Content PubMed PubMed Citation Articles by Heupel, R. Articles by Heldt, H. W. Agricola Articles by Heupel, R. Articles by Heldt, H. W.

Metabolism and Enzymology

Compartmentation Studies on Spinach Leaf Peroxisomes ¹

Evidence for Channeling of Photorespiratory Metabolites in Peroxisomes Devoid of Intact Boundary Membrane

Institut für Biochemie der Pflanze, Universität Göttingen, Untere Karspüle 2, 3400 Göttingen, Federal Republic of Germany, Pflanzenphysiologisches Institut, Universität Göttingen, Untere Karspüle 2, 3400 Göttingen, Federal Republic of Germany

In concurrence with earlier results, the following enzymes showed latency in intact spinach (Spinacia oleracea L.) leaf peroxisomes: malate dehydrogenase (89%), hydroxypyruvate reductase (85%), serine glyoxylate aminotransferase (75%), glutamate glyoxylate aminotransferase (41%), and catalase (70%). In contrast, glycolate oxidase was not latent. Aging of peroxisomes for several hours resulted in a reduction in latency accompanied by a partial solubilization of the above mentioned enzymes. The extent of enzyme solubilization was different, being highest with glutamate glyoxylate aminotransferase and lowest with malate dehydrogenase. Osmotic shock resulted in only a partial reduction of enzyme latency. Electron microscopy revealed that the osmotically shocked peroxisomes remained compact, with smaller particle size and pleomorphic morphology but without a continuous boundary membrane. Neither in intact nor in osmotically shocked peroxisomes was a lag phase observed in the formation of glycerate upon the addition of glycolate, serine, malate, and NAD. Apparently, the intermediates, glyoxylate, hydroxypyruvate, and NADH, were confined within the peroxisomal matrix in such a way that they did not readily leak out into the surrounding medium. We conclude that the observed compartmentation of peroxisomal metabolism is not due to the peroxisomal boundary membrane as a permeability barrier, but is a function of the structural arrangement of enzymes in the peroxisomal matrix allowing metabolite channeling.

This article has been cited by other articles:

				S. Timm, A. Nunes-Nesi, T. Parnik, K. Morgenthal, S. Wienkoop, O. Keerberg, W. Weckwerth, L. A. Kleczkowski, A. R. Fernie, and H. Bauwe A Cytosolic Pathway for the Conversion of Hydroxypyruvate to Glycerate during Photorespiration in Arabidopsis PLANT CELL, October 1, 2008; 20(10): 2848 - 2859. [Abstract] [Full Text] [PDF]

				A. S. Raghavendra, S. Reumann, and H. W. Heldt Participation of Mitochondrial Metabolism in Photorespiration . Reconstituted System of Peroxisomes and Mitochondria from Spinach Leaves Plant Physiology, April 1, 1998; 116(4): 1333 - 1337. [Abstract] [Full Text]

				S. Reumann, E. Maier, R. Benz, and H. W. Heldt The Membrane of Leaf Peroxisomes Contains a Porin-like Channel J. Biol. Chem., July 21, 1995; 270(29): 17559 - 17565. [Abstract] [Full Text] [PDF]