Microenvironmental pH changes in immobilized cephalosporin C acylase during a proton-producing reaction and regulation by a two-stage catalytic process. (January 2017)

• Record Type: Journal Article
• Authors: Luo, Hui; Zhu, Linlin; Chang, Yanhong; Liu, Xiuhong; Liu, Zijia; Sun, Hongxu; Li, Xi; Yu, Huimin; Shen, Zhongyao
• Is Part Of: Bioresource technology. Volume 223(2017)
• Page Start: 157
• Page End: 165
• Publication Date: 2017-01
• Subjects: Cephalosporin C acylase -- Immobilized enzyme -- Two-stage catalytic process -- Intraparticle pH -- Operational stability; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2016.10.038
• Languages: English
• ISSNs: 0960-8524

Abstract

Highlights: Intraparticle pH in immobilized cephalosporin C acylase was assayed and regulated. Intraparticle pH gradient during the reaction depends on the catalytic velocity. A high catalytic rate was related to a low operational stability of the enzyme. A novel two-stage catalytic process for proton-producing enzymes was proposed. The operational stability and reaction period could be ideally optimized. Abstract: Cephalosporin C acylase (CCA), a proton-producing enzyme, was covalently bound on an epoxy-activated porous support. The microenvironmental pH change in immobilized CCA during the reaction was detected using pH-sensitive fluorescein labeling. The high catalytic velocity of the initial stage of conversion resulted in a sharp intraparticle pH gradient, which was likely the key factor relating to low operational stability. Accordingly, a novel strategy for a two-stage catalytic process was developed to reduce the reaction rate of stage I at a low temperature to preserve enzymatic activity and to shorten the duration of catalysis at a high reaction temperature in stage II. The reaction using the two-stage catalytic process (10–37 °C shift at 30 min) showed significantly improved stability compared with that of the single-temperature reaction at 37 °C (29 batches versus five batches, respectively) and a shorter catalytic period than the reaction at 10 °C (40 min versus 70 min, respectively).