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SUBCELLULAR FRACTIONS OF NORMAL HUMAN SUBSTANTIA NIGRA AND CAUDATE NUCLEUS; A STUDY OF THEIR MORPHOLOGY AND SOME ENZYMES INCLUDING GLUTAMATE DECARBOXYLASE AND CHOLINE ACETYLTRANSFERASE
Author(s) -
Hickey Susan M.,
Ansell G. B.,
Mitchell K.,
Pearce G. W.
Publication year - 1976
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.1471-4159.1976.tb05161.x
Subject(s) - substantia nigra , caudate nucleus , biochemistry , glutamate decarboxylase , choline acetyltransferase , acid phosphatase , succinate dehydrogenase , acetylcholinesterase , biology , chemistry , enzyme , microbiology and biotechnology , endocrinology , dopamine , central nervous system , dopaminergic
— Subcellular fractions have been prepared from normal human caudate nucleus and substantia nigra by a standard fractionation technique and the fractions assayed for the following enzymes, which were studied because of their relevance to neurotransmission and pathological change: glutamate decarboxylase (EC 4.1.1.15), choline acetyltransferase (EC 2.3.1.6), acetylcholinesterase (EC 3.1.1.7), acid phosphatase (EC 3.1.3.2) and succinate dehydrogenase (EC 1.3.99.1). The distribution of these enzymes was assessed in relation to the morphology of the fractions as observed by electron microscopy. As with preparations from animal cerebral cortex, acetylcholinesterase and acid phosphatase were found mainly in fractions known to contain plasma membranes, synaptosomal membranes and microsomes. The levels of choline acetyltransferase in fractions from the substantia nigra were too low to measure but, in the caudate nucleus, the enzyme was concentrated in the crude mitochondrial fraction (P 2 ), especially in the P 2 B and P 2 C subfractions. A high proportion of the glutamate decarboxylase activity was present in the P 2 fractions of the substantia nigra and caudate nucleus and, although the synaptosomal (P 2 B) fraction contained the enzyme, significant amounts were found in the mitochondrial (P 2 C) fraction. This may have been due to some contamination of the mitochondria with small synaptosomes. Succinate dehydrogenase showed a conventional bimodal distribution between synaptosomes and mitochondria with a concentration in the latter.