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Enzymatic Properties of Aspartate Kinase MutantA380H from Corynebacterium pekinense
CHEN Zhijie, WANG Peng, ZHAN Dongling, FANG Li, MIN Weihong
Journal of Jilin University Science Edition. 2017, 55 (05):
1336-1344.
By homologous sequence and protein structure analysis, we found that A380 was an absolutely conserved site of aspartate kinase, and performed the sitedirected mutagenesis, isolation, purification and characterization of the site. The results show that compared with the wild type (WT), the Vmax of the mutant A380H is increased by 4.28 folds. The optimum temperature of the mutant A380H is increased from 28 ℃ to 35 ℃, the optimum pH is still 7.5, and the halflife is shortened from 4.5 h to 3.5 h. The substrate inhibitors have inhibitory effects on WT and mutants, threonine and lysine show synergistic inhibition effects. However, threonine alone has an activation or inhibitory effect on A380H, Mg2+ and Ni2+have an activation effect on WT, 1,5 mmol/L of Cu2+ has an activation effect on A380H. Compared with WT, the inhibitory effect of methanol and isopropanol on A380H is enhanced. The inhibitory effect of nbutanol and acetonitrile on A380H is reduced and show activation.
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