Synthesis Optimization of L-Aspartic acid β-hydroxamate by a novel Enzyme, β-Aspartyl-γ-glutamyl transferase

Abstract

L-Aspartic acid β-hydroxamate or L-β-Aspartyl hydroxamate (BAH), water soluble- chemical compound currently obtains popularity due to its role in several important biochemical processes and to its bioactivities. The information regarding synthesis process of BAH is not available yet. Novel enzyme, β-aspartyl-γ-glutamyl transferase from Pseudomonas syringae can catalyze the transfer reaction of β-aspartyl moieties from β-aspartyl compounds to water or to hydroxylamine. In this study we describe the synthesis optimization of BAH using this novel enzyme. We prepared the L-β-aspartyl hydroxamate using L- asparagine as a donor substrate and hydroxylammonium chloride as an acceptor substrate. The effects of temperature, pH, concentrations of substrate donor and acceptor were investigated. Spectrophotometry and HPLC analyses were performed to determine the reaction products. The optimum synthesis reaction was observed in 60˚C. BAH synthesis was optimum at pH 6. The concentrations of donor and acceptor substrates affected the BAH production and the best concentrations of both substrates were 80 mM and 40 mM, respectively. The BAH production of 0.106 mM has been obtained under the optimized condition and it is approximately two-times higher than 0.047 mM produced under in standard reaction. In conclusion, biosynthesis of L-β-aspartyl hydroxamate using a novel enzyme, β- aspartyl-γ-glutamyl transferase from Pseudomonas syringae was successfully performed for the first time. Under the optimized conditions, two times higher L-β-aspartyl hydroxamate production was obtained.