Is there a high molecular weight glutamic acid decarboxylase ?

Gel-filtration chromatography from crude extracts of mouse brain indicates the presence of a high molecular weight (HMW) (more than 750 kd) and a low molecular weight (LMW) (87.5 Kd) glutamic acid decarboxylase (GAD) when they are concentrated prior chromatography either by precipitation with salts...

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Bibliographic Details
Published in:Neurochemical research 1992-04, Vol.17 (4), p.339-343
Main Authors: Mora, M. P rez-de la, Rizo-Silva, A. B., M ndez-Franco, J.
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Animals
biochemical characteristics
Biological and medical sciences
brain
Brain - enzymology
Chromatography, Gel
Enzymes and enzyme inhibitors
forms
Fundamental and applied biological sciences. Psychology
glutamate decarboxylase
Glutamate Decarboxylase - chemistry
Lyases
Mice
Molecular Weight
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Summary:Gel-filtration chromatography from crude extracts of mouse brain indicates the presence of a high molecular weight (HMW) (more than 750 kd) and a low molecular weight (LMW) (87.5 Kd) glutamic acid decarboxylase (GAD) when they are concentrated prior chromatography either by precipitation with salts or ethanol. Kinetically both peaks of GAD-activity exhibit an almost identical Km for L-glutamate. Only LMW-GAD appears if the concentration step is carried out by ultrafiltration or if the extract is chromatographied without the concentrating step. HMW-GAD disappears from the chromatographic profiles if ethanolic extracts of GAD are treated with Triton X-100 before the chromatographic procedure. The sodium sulfate precipitation of a previously separated LMW-GAD gives rise to the reappearance of a HMW-GAD peak. Apparently HMW-GAD does not exist as a different molecular entity; indeed it may be an artefactual aggregation of LMW-GAD.
ISSN:0364-3190
1573-6903
DOI:10.1007/BF00974575