| | 1 | Author
| Remigius Manderscheid, Aloysius Wild | Requires cookie* | | | Title
| Characterization of Glutamine Synthetase of Roots, Etiolated Cotyledons and Green Leaves from Sinapis alba (L.)  | | | | Abstract
| Glutamine synthetase of roots, etiolated cotyledons and green leaves from mustard plants cannot all clearly be separated by DEAE-Sephacel chromatography. However, the enzyme of the roots, etiolated cotyledons and green leaves, respectively, differed in the kinetic properties deter mined in the crude extract. The root enzyme showed a pH-optimum of about 6.9, a K m value of 3 m M for glutamate and a temperature optimum at 48 °C. Glutamine synthetase of etiolated cotyledons possessed a Km for glutamate of 6 or 12 m M , depending on the dithioerythritol con centration in the homogenisation buffer and a temperature optimum at 46 °C. The enzyme of green leaves was characterized by a temperature optimum at 40 °C, a pH-optimum at about 7.4 and a low glutamate affinity with positive cooperative substrate binding. Based on isolation of chloroplasts and identification of glutamine synthetase the enzyme of green leaves seems to be the chloroplastic form. This enzyme was purified by DEAE-Sephacel, hydroxylapatite and Sephacryl S-300 chromatography. Affinity for glutamate and M g S04 of the purified enzyme differed from that found in the crude extract. The function of the different isoenzymes is discussed. Intro du ction | | | |
Reference
| Z. Naturforsch. 41c, 712 (1986); received March 17 1986 | | | |
Published
| 1986 | | | |
Keywords
| Enzyme Purification, Glutamine Synthetase, Isoenzymes, Photorespiration, Sinapis alba | | | |
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| default:Reihe_C/41/ZNC-1986-41c-0712.pdf | | | | Identifier
| ZNC-1986-41c-0712 | | | | Volume
| 41 | |
| 2 | Author
| Joseph Veser, P. Eter, G. | Requires cookie* | | | Title
| Purification and Properties of a Catechol Methyltransferase of the Yeast Candida tropicalis | | | | Abstract
| In an effort to investigate catechol methyltransferase activity in sources other than mam m alian tissues and cells, a high level o f enzyme activity was found in the yeast fungus Candida tropicalis CBS 94. Partial purification o f the enzyme (approx. 550 fold with a recovery o f 7%) could be achieved by using ion-exchange and gel filtration techniques. The molecular w eight was estimated at 32,000 ± 2,000 by gel filtration on Sephadex G-100. In isoelectric focusing experiments on Sephadex G-75 the enzym e exhibited a pl-value o f 5.0 ± 0.1. In contrast to catechol methyltransfer ase from various m am m alian tissues the enzyme activity was prepared from the pH 5-sediment. The substrate specifity is com parable to other catechol methyltransferases. | | | |
Reference
| Z. Naturforsch. 34c, 709 (1979); received April 24 1979 | | | |
Published
| 1979 | | | |
Keywords
| Catechol Methyltransferase, Yeast Fungus, Candida tropicalis CBS 94, Enzyme Purification, Catechols | | | |
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| default:Reihe_C/34/ZNC-1979-34c-0709.pdf | | | | Identifier
| ZNC-1979-34c-0709 | | | | Volume
| 34 | |
| 3 | Author
| Matthias Höpfner, Georg Reifferscheid, Aloysius Wild | Requires cookie* | | | Title
| Molecular Composition of Glutamine Synthetase of Sinapis alba L | | | | Abstract
| Chloroplastic glutamine synthetase of Sinapis alba, purified to homogeneity by a simple three step procedure, revealed a molecular weight of about 395 kDa. The native enzyme is composed of eight subunits of identical molecular weight (about 50 kDa (each), although isoelectrofocusing yielded six distinct bands in the pH 5.6 region of the gel. Labelling of the enzyme with the glutamate analogue herbicide [ 14 C]phosphinothricin and with [y-32 P]ATP indicated that glutamine synthetase has eight reactive centers per molecule. The native enzyme dissociated into two enzymatically active subaggregates of about 195 kDa after Mg 2+ deprivation. | | | |
Reference
| Z. Naturforsch. 43c, 194—198 (1988); received November 26 1987 | | | |
Published
| 1988 | | | |
Keywords
| Active Centers, Enzyme Purification, Enzyme Structure, Glufosinate, Glutamine Synthetase, Phosphinothricin | | | |
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| default:Reihe_C/43/ZNC-1988-43c-0194.pdf | | | | Identifier
| ZNC-1988-43c-0194 | | | | Volume
| 43 | |
| 4 | Author
| M. Aria, C. Alvarez-Ossorioa, FranciscoJ G M Uriana3, FranciscoF. De La Rosab, AngelM. Relimpioa | Requires cookie* | | | Title
| Purification and Characterization of Nitrate Reductase from the Halophile Archaebacterium Haloferax mediterranei | | | | Abstract
| Nitrate reductase is induced in cells o f H aloferax mediterranei by the presence o f nitrate upon anaerobic conditions. This enzyme was purified more than 35-fold with a yield o f 49%. Densitograms o f polyacrylamide gel electrophoresis show the preparation to be 85% purity. The best enzyme preparation has a specific activity o f 13.6 U /m g protein. It is the first halo philic nitrate reductase that has been purified near to homogeneity. The purification consists o f five steps: an amm onium sulphate precipitation and four successive gel chromatographies with Sepharose C L -4B, calcium phosphate, D EAE-Sephacel and Sephacryl S-200. An average Mr o f 170,000 was estimated by gel chromatography and non-denaturing gel electrophoresis. Effectiveness o f electron donors, cofactors and inhibitors are reported. At low salt concentra tion the halophilic nitrate reductase was inactivated follow ing first-order kinetics. The K m for nitrate depends on salt concentration and shows values in the range from 2.5 to 6.7 m M . | | | |
Reference
| Z. Naturforsch. 47c, 670—6 (1992); received April 7/June 15 1992 | | | |
Published
| 1992 | | | |
Keywords
| Halophilic Nitrate Reductase, Enzyme Purification, Enzyme Characterization, Haloferax mediterranei | | | |
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| default:Reihe_C/47/ZNC-1992-47c-0670.pdf | | | | Identifier
| ZNC-1992-47c-0670 | | | | Volume
| 47 | |
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