PMID:6319365
| Citation |
Smith, CJ, Deutch, AH and Rushlow, KE (1984) Purification and characteristics of a gamma-glutamyl kinase involved in Escherichia coli proline biosynthesis. J. Bacteriol. 157:545-51 |
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| Abstract |
gamma-Glutamyl kinase, the first enzyme of the proline biosynthetic pathway, was purified to homogeneity from an Escherichia coli strain resistant to the proline analog 3,4-dehydroproline. The enzyme had a native molecular weight of 236,000 and was apparently comprised of six identical 40,000-dalton subunits. Enzymatic activity of the protein was detectable only in assays containing highly purified gamma-glutamyl phosphate reductase, the second enzyme of the proline pathway. Plots of gamma-glutamyl kinase activity as a function of glutamate concentration were sigmoidal, with a half-saturation value for glutamate of 33 mM, whereas plots of enzyme activity as a function of ATP concentration displayed typical Michaelis-Menten kinetics with a Km for ATP of 4 X 10(-4) M. Enzyme activity was insensitive to the glutamate analog L-methionine-DL-sulfoximine, but ADP was a potent competitive inhibitor. Characteristics of the enzyme were compared with those of a gamma-glutamyl kinase partially purified from a 3,4-dehydroproline-sensitive E. coli. These results indicated that the only major difference was that the enzyme from the 3,4-dehydroproline-resistant strain was 100-fold less sensitive to feedback inhibition by proline. |
| Links | |
| Keywords |
Escherichia coli/enzymology; Kinetics; Macromolecular Substances; Molecular Weight; Phosphotransferases/isolation & purification; Phosphotransferases/metabolism; Phosphotransferases (Carboxyl Group Acceptor); Proline/biosynthesis; Proline/pharmacology |
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