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Homotropic allosteric control in clostridial glutamate dehydrogenase: Different mechanisms for glutamate and NAD + ?
Author(s) -
Hamza Muaawia A.,
Engel Paul C.
Publication year - 2008
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/j.febslet.2008.04.049
Subject(s) - cooperativity , allosteric regulation , nad+ kinase , glutamate dehydrogenase , cofactor , chemistry , cooperative binding , glutamate receptor , biochemistry , enzyme , kinetics , stereochemistry , mutant , dehydrogenase , biophysics , biology , receptor , physics , quantum mechanics , gene
Clostridial glutamate dehydrogenase mutants with the 5 Trp residues in turn replaced by Phe showed the importance of Trp 64 and 449 in cooperativity with glutamate at pH 9. These mutants are examined here for their behaviour with NAD + at pH 7.0 and 9.0. The wild‐type enzyme displays negative NAD + cooperativity at both pH values. At pH 7.0 W243F gives Michaelis–Menten kinetics, and the same behaviour is shown by W243F and also W310F at pH 9.0, but not by W64F or W449F. W243 and W310 are apparently much more important than W64 and W449 for the coenzyme negative cooperativity, implying that different conformational transitions are involved in cooperativity with the coenzyme and with glutamate.