Open AccessReversible dissociation of aspartokinase I/homoserine dehydrogenase I from Escherichia coli K 12
Author(s) -
VERON Michel,
GUILLOU Yvonne,
FAZEL Akram,
COHEN Georges N.
Publication year - 1985
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1985.tb09133.x
Subject(s) - tetramer , escherichia coli , chemistry , protein subunit , homoserine , dissociation (chemistry) , biochemistry , dehydrogenase , enzyme , stereochemistry , organic chemistry , quorum sensing , gene , virulence
Dimers of aspartokinase I/homoserine dehydrogenase I from Escherichia coli K 12 have been isolated under very mild conditions. The dimers which cannot be distinguished from the tetramers by their kinetic properties, reassociate in the presence of potassium ions or L ‐aspartate. The selective sensitivity of aspartokinase I/homoserine dehydrogenase I to mild proteolytic digestion of dimers has been used to probe the reassociation reaction under the conditions of aspartokinase assay. We demonstrate that rapid reassociation occurs and that the protein species present in the assay when dimers are used to test the activity is tetrameric. These results confirm the previously proposed model for the subunit association of aspartokinase I/homoserine dehydrogenase I.