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Structural kinetics of the allosteric transition of aspartate transcarbamylase produced by physiological substrates
Author(s) -
Tsuruta Hirotsugu,
Sano Takayuki,
Vachette Patrice,
Taue Patrick,
Moody Michael F.,
Wakabayashi Katsuzo,
Amemiya Yoshiyuki,
Kimura Kazumoto,
Kihara Hiroshi
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80706-o
Subject(s) - aspartate carbamoyltransferase , allosteric regulation , carbamyl phosphate , kinetics , protein quaternary structure , chemistry , enzyme , substrate (aquarium) , biophysics , stereochemistry , biochemistry , biology , ecology , physics , quantum mechanics , protein subunit , gene
We have studied the kinetics of the quaternary structure change associated with the allosteric transition of aspartate transcarbamylase (ATCase) ( E. coli ), inducing this change by exposure to the natural substrates (carbarnyl phosphate and L‐aspartate). The presence of 30% ethylene glycol slowed the quaternary structure change sufficiently for it to be followed by stopped‐flow X‐ray scattering at − 5°C. After adding substrates to the enzyme, the change occurred, with a half‐life of a few seconds, yielding a mixture of the two standard quaternary structures (or, conceivably, a state intermediate between them). This mixture persisted until the enzyme reduced the substrate concentration below a threshold value.