Molecular and Cellular Biology
Glyoxylate cycle in the epiphyseal growth plate: Isocitrate lyase and malate synthase identified in mammalian cartilage
Version of Record online: 22 FEB 2005
Copyright © 1989 Wiley-Liss, Inc.
The Anatomical Record
Volume 223, Issue 4, pages 357–362, April 1989
How to Cite
Davis, W. L., Jones, R. G., Farmer, G. R., Matthews, J. L. and Goodman, D. B. P. (1989), Glyoxylate cycle in the epiphyseal growth plate: Isocitrate lyase and malate synthase identified in mammalian cartilage. Anat. Rec., 223: 357–362. doi: 10.1002/ar.1092230402
- Issue online: 22 FEB 2005
- Version of Record online: 22 FEB 2005
- Manuscript Accepted: 8 SEP 1988
- Manuscript Received: 28 SEP 1987
Peroxisomes were identified in chondrocytes from all zones of the mammalian epiphyseal growth plate by using light microscopic techniques for the cytochemical demonstration of catalase, the marker enzyme for these organelles. Additional cytochemistry showed the presence of malate-synthase-positive structures within the chondrocytes. The latter enzyme, also associated with peroxisomes, is unique to the glyoxylate shunt, a metabolic pathway thought to be absent in vertebrate tissues. The glyoxylate cycle allows the net conversion of lipid to carbohydrate, i.e., gluconeogenesis. Biochemical studies on growth plate cartilage indicate that this tissue has the capacity to carry out cyanide-insensitive B-oxidation of fatty acids. The latter takes place in a nonmitochondrial compartment, most likely the peroxisomal compartment. Additionally, both of the unique enzymes associated with the glyoxylate cycle, i.e., isocitrate lyase and malate synthase, were also identified in a cell-free homogenate of this cartilage. These studies indicate that cartilage, a poorly vascularized tissue characterized by its low oxygen tension and anaerobic glycolysis, may have the capacity to convert lipid to carbohydrate, i.e., gluconeogenesis via the glyoxylate pathway. In this way, cartilage may be unique among mammalian tissues.