Immunoelectron microscopic study of a new D-amino acid oxidase-immunoreactive subcompartment in rat liver peroxisomes.
We report the presence of a new subcompartment in rat liver peroxisomal matrix in which only D-amino acid oxidase is localized and other matrix enzymes are absent. By electron microscopic observation, the rat liver peroxisome has generally been considered to consist of a single limiting membrane, an electron-dense crystalline core, and a homogeneous matrix. Immunohistochemical staining for D-amino acid oxidase by the protein A-gold technique revealed the presence of a small area in the matrix that was immunoreactive for the enzyme and was less electron-dense than the surrounding matrix. The localization of D-amino acid oxidase in this small area of the peroxisomal matrix was confirmed by immunoelectron microscopy on freeze-substituted tissues processed without chemical fixation. To analyze the characteristics of the electron-lucent area, immunoreactivity for various peroxisomal enzymes, including catalase, acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein, 3-ketoacyl-CoA thiolase, L-alpha-hydroxy acid oxidase (isozyme B), and glycolate oxidase (isozyme A), was assayed. The electron-lucent area was negative for all of these. By double staining for D-amino acid oxidase and catalase, using colloidal gold particles of different sizes, these enzymes were shown to be located in separate areas in the matrix.
Usuda
N
N
Department of Anatomy and Cell Biology, Shinshu University School of Medicine, Matsumoto, Japan.
Yokota
S
S
Ichikawa
R
R
Hashimoto
T
T
Nagata
T
T
D000818:Animals; D002374:Catalase / Q000032:analysis; D003102:Colloids; D003605:D-Amino-Acid Oxidase / Q000032:analysis*; D006046:Gold; D007150:Immunohistochemistry; D008099:Liver / Q000201:enzymology / Q000648:ultrastructure*; D008297:Male; D008830:Microbodies / Q000201:enzymology*; D016253:Microscopy, Immunoelectron; D051381:Rats; D011919:Rats, Inbred Strains; D013205:Staphylococcal Protein A
D003102:Colloids; D013205:Staphylococcal Protein A; D006046:Gold; D002374:Catalase; D003605:D-Amino-Acid Oxidase