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THE REGIONAL DISTRIBUTION OF CYTIDINE 5′‐MONOPHOSPHO‐ N ‐ACETYL‐NEURAMINIC ACID SYNTHETASE IN CALF BRAIN
Author(s) -
Van Den Eijnden D. H.,
Meems L.,
Roukema P. A.
Publication year - 1972
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1972.tb06210.x
Subject(s) - enzyme , cytidine , biochemistry , white matter , neuraminic acid , biology , transferase , nucleus , enzyme assay , sialic acid , chemistry , microbiology and biotechnology , medicine , radiology , magnetic resonance imaging
—The enzyme cytidine 5′‐monophospho‐ N ‐acetylneuraminic acid synthetase was studied in different parts of the calf brain. Characterization of partial purified enzyme preparations from cortical grey matter and corpus callosum by means of pH optima and K m values, showed the enzyme of grey and white brain areas to be identical. Unexpectedly the regional differences of the enzyme activities per g wet tissue and per mg protein were very slight. From the presence of the enzyme in pure white brain areas, which are known to be poor in neuronal perikarya, and the fact that the enzyme is localized in the cell nucleus, we concluded that cytidine 5′‐monophospho‐ N ‐acetylneuraminic acid is produced in glia cell nuclei and that it is very likely that biosynthesis of sialo‐glycoproteins and/or ganglio‐sides occurs within glia cells. The enzyme activity per μmol DNA‐P is somewhat higher in grey than in white regions, indicating a slightly higher activity per neuronal than per glial nucleus. The regional differences of lipid and protein‐bound sialic acid and RNA show a striking similarity and contrast to those of the enzyme. These differences are interpreted in terms of a differential content in neurons and glia cells.