Abstract:
:Escherichia coli glutamine synthetase (GS) was inactivated by a nonenzymic mixed-function oxidation system composed of ascorbate, O2, and Fe(III). Partial inactivation of GS by this system leads to the formation of hybrid GS molecules (dodecamers) composed of both active and inactive subunits. Subunit interactions in these hybrid molecules are weaker than in the native enzyme, as indicated by the kinetics of subunit dissociation in the presence of 4 M urea. Heterologous subunit interactions in these hybrid molecules do not affect the affinity of active subunits for glutamate. Incubation of partially adenylylated GS preparations (n = 6.7) with the ascorbate system in the absence of substrates leads to preferential oxidative inactivation of unadenylylated subunits, whereas incubation in the presence of ATP and glutamate leads to preferential inactivation of adenylylated subunits.
journal_name
Proc Natl Acad Sci U S Aauthors
Nakamura K,Stadtman ERdoi
10.1073/pnas.81.7.2011subject
Has Abstractpub_date
1984-04-01 00:00:00pages
2011-5issue
7eissn
0027-8424issn
1091-6490journal_volume
81pub_type
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