| | 1 | Author
| M.Arianne Nagel, ThomasH. Artm Ann | Requires cookie* | | | Title
| Glutamate Dehydrogenase from Medicago sativa L., Purification and Comparative Kinetic Studies of the Organ-Specific Multiple Forms  | | | | Abstract
| NAD-specific glutamate dehydrogenase [L-glutamate: N A D + oxidoreductase (deaminating) EC 1.4.1.2] from Medicago sativa constitutes organ-specific patterns o f isoenzymes. The isoenzyme-pattems o f seeds (GDH-I) and roots (GDH-II) were purified 1520-fold and 92-fold, respectively. All isoenzymes o f both patterns remain stable throughout the purification procedures. Isoenzyme a7, the only isoenzyme common to both patterns was isolated from the GDH-I pattern. The three enzyme preparations were found to be identical in pH optima, substrate specificity and general ki netic properties. A comparative kinetic analysis revealed no pronounced differences between the various kinetic constants evaluated for the three enzyme preparations. Furthermore an identical order of substrate binding and product release could be established. Both initial rate measure ments and product inhibition studies are consistent with an ordered ternary-binary kinetic mecha nism. The results suggest that tissue-specific enzyme multiplicity of plant glutamate dehydrogen ase is not related to differences in general or kinetic properties. | | | |
Reference
| Z. Naturforsch. 35c, 406 (1980); received January 71980 | | | |
Published
| 1980 | | | |
Keywords
| Medicago sativa, Glutamate Dehydrogenase, Multiple Enzyme Forms, Purification, Kinetic Pro perties | | | |
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| default:Reihe_C/35/ZNC-1980-35c-0406.pdf | | | | Identifier
| ZNC-1980-35c-0406 | | | | Volume
| 35 | |
| 2 | Author
| Heinz-W Alter, Scheid, Adelheid Ehmke, Thomas Hartm | Requires cookie* | | | Title
| Plant NAD-Dependent Glutamate Dehydrogenase. Purification, Molecular Properties and Metal Ion Activation of the Enzymes from Lemna minor and Pisum sativum | | | | Abstract
| Glutamate dehydrogenase (L-glutamate: N A D + oxidoreductase (deaminating) EC 1.4.1.2) has been purified to homogeneity from Lemna minor and seeds o f Pisum sativum. As established by polyacrylamide gel electrophoresis the Pisum-enzyme constitutes a multiple pattern o f seven char ge isoenzymes whereas the Lemna enzyme shows one single protein band. Molecular weights of 230 000 were calculated for both enzymes by sedimentation equilibrium measurements (Pisum-enzyme]I and comparative gel filtration (Lemna-enzyme). Sodium dodecyl sulfate gel electropho resis and electron microscopic observations revealed that both enzymes are composed of four identical subunits (molecular weight 58 500) arranged in a tetraedric structure. The amino acid compositions of both enzymes are similar to those of various hexameric glutamate dehydrogen ases. The N-terminal amino acid of the Pisum-enzyme is alanine. Both enzymes require Ca2+ for maximal catalytic activity. For the Lemna-enzyme the K0.s values for Ca2+ are 22 /j.m (NADH-de-pendent reaction) and 4 piM (N A D +-dependent reaction), respectively. Ca2+ which to some extent can be replaced by Zn2+ does not affect the enzyme aggregation but seems to govern a reversible equilibrium between catalytically active and inactive enzyme forms. | | | |
Reference
| Z. Naturforsch. 35c, 213—221 (1980); received November 21 1979 | | | |
Published
| 1980 | | | |
Keywords
| Lemna minor, Pisum sativum, Glutamate Dehydrogenase, Purification, Molecular Properties, Me tal Ion Activation | | | |
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| default:Reihe_C/35/ZNC-1980-35c-0213.pdf | | | | Identifier
| ZNC-1980-35c-0213 | | | | Volume
| 35 | |
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