Abstract
2-Amino-3-ketobutyrate CoA ligase (KBL) of Escherichia coli is a member of the α-oxoamine synthase family; it catalyzes the condensation reaction between glycine and acetyl CoA to yield 2-amino-3-ketobutyrate.We have previously shown that KBL catalyzes the exchange of pro-R hydrogen of glycine with protons in the medium; however, the kinetics of this reaction has never been determined. In this study, we calculated the kinetic parameters of this exchange reaction by using different concentrations of [2RS- 3H2: 2-14C] glycine. The rate of the exchange reaction was determined by measuring the 3H/14C ratio in recovered [2S- 3H: 2-14C]glycine. The Lineweaver-Burk plot showed that K m and k cat of this reaction were 3.8 × 10-3 M and 0.22 S-1, respectively. On the other hand, K m and k cat values of the overall KBL-mediated catalysis were correspondingly 1.23 × 10-2M and 1.19 S-1. Thus, the rate of the exchange reaction was almost five times lower than that of overall KBL catalysis.
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Jamil, F. Kinetics of the exchange reaction catalyzed by 2-amino-3-ketobutyrate CoA ligase. Front. Biol. 10, 503–507 (2015). https://doi.org/10.1007/s11515-015-1378-7
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DOI: https://doi.org/10.1007/s11515-015-1378-7