Glutamate dehydrogenases from tissues of the ribbed musselModiolus demissus: ADP activation and possible physiological significance
✍ Scribed by Reiss, Paul M. ;Pierce, Sidney K. ;Bishop, Stephen H.
- Publisher
- John Wiley and Sons
- Year
- 1977
- Tongue
- English
- Weight
- 536 KB
- Volume
- 202
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Abstract
Glutamate dehydrogenase (E.C. 14.1.3) was localized in the mitochondria from heart, gill, mantle and hepatopancreas of this euryhaline bivalve mollusc. Activity levels were low (0.1‐0.4 μmoles/min/g wet weight) in all tissues when assayed in the glutamate forming direction. Partially purified gill mitochondrial GDH was most active at pH 8.5. The rate in the glutamate deaminating direction was 10‐20% of the rate in the glutamate forming direction. ADP at apparent K~a~ concentrations of 90 μM (glutamate formation) and 170 μM (glutamate deamination) enhanced GDH activity, 8‐ and 4‐fold respectively. GDH, in vivo, is probably in the activated form and appears to function in glutamate synthesis rather than ammonia formation. However, based on the low activities obtained, the role of GDH in salinity induced amino acid synthesis seems minimal.