Enterococcus faecium d-aspartate ligase (Asl_fm) is a peptide bond-forming enzyme that is involved in the peptidoglycan assembly pathway. It catalyzes the ATP-dependent ligation of the β-carboxylate of D-Asp to the ε-amino group of L-Lys in the nucleotide precursor UDP- MurNAc-pentapeptide. The enzyme is of interest as a target of new, potential, narrow-spectrum antibiotics directed against multiresistant E. faecium. The kinetic mechanism of Asl_fm has not been fully characterized. To determine it, a progress curve analysis of Asl_fm catalytic process using pyruvate kinase/lactate dehydrogenase ATPase detection assay was performed. With an inspection of the shape of measured progress curves and the results of specific qualitative experiments, the Asl_fm reaction mechanism was singled out. The proposed Asl_fm kinetics reaction scheme was evaluated by fitting the parameters of the corresponding differential equations to progress curves using the computer program ENZO. The complete kinetic analysis result is consistent with the substrate binding order 1) ATP, 2) D-Asp, and 3) UDP-MurNAc-pentapeptide. The analysis suggests that slowly establishing non-productive equilibria between the free and ATP-bound enzyme with the participating pentapeptide are responsible for initial reaction burst followed by a steady-state period before the complete depletion of the reactant added in the lowest concentration.

粪肠球菌 d-天冬氨酸连接酶（Asl _fm）是一种肽键形成酶，与肽聚糖组装途径有关。它催化核苷酸前体UDP-Mur N Ac-五肽中D-Asp的β-羧酸盐与L-Lys的ε-氨基的ATP依赖性连接。该酶作为针对多重耐药性屎肠球菌的新型，潜在的，窄谱抗生素的靶标而引起人们的兴趣。Asl _fm的动力学机制尚未完全表征。为了确定它，Asl _fm的进度曲线分析丙酮酸激酶/乳酸脱氢酶ATPase检测法进行了催化过程。通过检查测得的进度曲线的形状和特定定性实验的结果，确定了Asl _fm反应机理。所提出的黄芪甲甙_FM通过拟合对应的差分方程的参数进步使用计算机程序ENZO曲线动力学反应方案进行评价。完整的动力学分析结果与底物结合顺序1）ATP，2）D-Asp和3）UDP-Mur N一致Ac-五肽。分析表明，与参与的五肽缓慢建立游离酶和ATP结合酶之间的非生产性平衡是造成初始反应爆发的原因，随后是稳态阶段，然后以最低浓度添加的反应物被完全消耗掉。