Abstract: The Burkholderia cepecia 1003 screened by the authors’ laboratory, which contains hydantoinase and N-carbamoylase activities, was used to prepare D-phenylalanine on a large scale. The dynamic parameters of the whole bioconversion process were measured, and the results showed that k_r was 3.975×10^-3min^-1,K_m and r_m of hydantoinase and N-carbamoylase were 16.7894 mmol•L^-1, 0.82688 mmol•L^-1, 0.6127 mmol•L^-1•min^-1 and 4.828×10^-4mmol•L^-1•min^-1，respectively.Simulation was made including processes of dissolution, racemization, hydrolysis of D-BH and hydrolysis of N-carbamyl phenylalanine.The significance of parameters in this model was investigated and these parameters were optimized. The result showed that the reaction rate of D-BH hydrolysis was higher than that of N-carbamyl phenylalanine hydrolysis,the latter was the limiting step of the whole process. Promotion of N-carbamoylase activity was helpful to D-phenylalanine production. Another result was that the rate of L-BH racemization was the main factor, which influenced the conversion of racemic BH.

摘要： 采用自行筛选的兼有海因酶和N-氨甲酰氨基酸水解酶活性的Burkholderia cepecia 1003菌种，利用海因酶法大规模制备D-苯丙氨酸，对其中涉及的各过程的动力学参数进行了测定.结果表明:L-苄基海因的消旋速率常数为3.975×10^-3min^-1；海因酶的米氏常数为16.7894 mmol•L^-1，最大反应速率为0.6127 mmol•L^-1•min^-1；N-氨甲酰氨基酸水解酶的米氏常数为0.82688 mmol•L^-1，最大反应速率为4.828×10^-4 mmol•L^-1•min^-1.对DL-5-苄基海因的溶解、L-苄基海因的消旋、D-海因的水解开环及其中间产物（N-氨甲酰苯丙氨酸）的水解脱酰氨过程建立了动力学模型，并在此基础上进行了动力学参数显著性分析和优化.结果表明：对于这一级联酶转化反应，D-海因酶的水解反应是快速反应，而N-氨甲酰氨基酸脱氨甲酰的反应速率极小，是该过程的控制步骤.提高氨甲酰水解酶的活力将有助于提高总体的转化速率，而L-海因的消旋速率则是影响外消旋苄基海因转化率的主要因素.