0000000000749430
AUTHOR
Matthias Höpfner
Detection of a Single Gene Encoding Glutamine Synthetase in Sinapis alba (L.)
Summary Ion-exchange chromatography of glutamine synthetase polypeptides (GS; EC 6.3.1.2) from green leaves and the roots of Sinapis alba yielded identical elution patterns. This is likewise true for GS from etiolated cotyledons. As we have previously demonstrated the identity of GS-enzymes from etiolated and green leaf tissues, the obviously very similar charge properties of GS-proteins indicate the eventual existence of only one type of GS in all mustard plant organs. To further prove this possibility, Southern blot analysis of mustard DNA was carried out using hybridization probes specific to different GS-isoforms. Concluding from the relative strength of the hybridization signals, the G…
The Effect of Different Growth Light Intensities On Photosystem II Components
Light is essential not only as the driving force of photosynthesis but also as a trigger and a modulator of morphogenic processes. Physiological and morphological factors are modified when plants are grown at different light intensities and light qualities. Many plants are able to adapt the photosynthetic rate to the environmental factor light in a wide range. Low-light (LL) and high- light(HL) plants differ in a number of component processes of photosynthesis (1, 2). The adaptation process consists in a complex well coordinated change of many structural and biochemical components of the series of photosynthetic subprocesses (3).
Molecular Composition of Glutamine Synthetase of Sinapis alba L.
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 [14C]phosphinothricin and with [γ-32P]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 Mg2+ deprivation.