ISSN:
1432-2048
Keywords:
Glutamine synthetase
;
Legume
;
Rhizobium symbiosis
;
Nitrogen assimilation
;
Phaseolus (glutamine synthetase)
;
Rhizobium
;
Root nodule
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Two forms of glutamine synthetase (GS) have been purified to apparent homogeneity from the plant fraction of Phaseolus vulgaris root nodules. One of these forms appears identical to the form of the enzyme found in roots but the other is probably specifically associated with the nodule. Free-living Rhizobium phaseoli also contain two forms of GS both of which have different molecular weights from the plant enzymes. Bacteroids contain solely the higher-molecular-weight form of rhizobial GS. There are only minor differences between the plant enzymes in Km or S0.5 values for the synthetase-reaction substrates and both forms have identical molecular weights of the holoenzyme (380,000 daltons) and its sub-units (41,000 daltons). They can be separated by ion-exchange chromatography on diethylaminoethyl-Sephacel and by native polyacrylamide-gel electrophoresis. The only other distinguishing feature observed is that the ratio of transferase: synthetase activity of the root form is threefold greater than that of the nodule-specific GS.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00405189
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