Determination of the enzyme reaction rate in a differential fixed-bed reactor: A case study

Citation
Ea. Baruque et al., Determination of the enzyme reaction rate in a differential fixed-bed reactor: A case study, BRAZ J CH E, 18(1), 2001, pp. 1-11
Citations number
18
Categorie Soggetti
Chemical Engineering
Journal title
BRAZILIAN JOURNAL OF CHEMICAL ENGINEERING
ISSN journal
01046632 → ACNP
Volume
18
Issue
1
Year of publication
2001
Pages
1 - 11
Database
ISI
SICI code
0104-6632(200103)18:1<1:DOTERR>2.0.ZU;2-K
Abstract
The reaction rate of starch hydrolysis catalyzed by a glucoamylase covalent ly bound to chitin particles was measured in a Differential Fixed-Bed React or (DFBR). Under selected test conditions the initial reaction rate may rep resent biocatalyst activity. Some aspects which influence measurement of th e initial reaction rate of an immobilized enzyme were studied: the amount o f desorbed enzyme and its hydrolytic activity, the extent of pore blockage of the biocatalyst caused by substrate solution impurities and the internal and external diffusional mass transfer effects. The results showed that th e enzyme glucoamylase was firmly bound to the support, as indicated by the very low amount of desorbed protein found in the recirculating liquid. Alth ough this protein was very active, its contribution to the overall reaction rate was negligible. It was observed that the biocatalyst pores were susce ptible to being blocked by the impurities of the starch solution. This latt er effect was accumulative, increasing with the number of sequential experi ments carried out. When the substrate solution was filtered before use, ver y reliable determinations of immobilized enzyme reaction rates could be per formed in the DFBR. External and internal diffusional resistences usually p lay a significant role in fixed-bed reactors. However, for the experimental system studied, internal mass transfer effects were not significant, and i t was possible to select an operational condition (recirculation flow rate value) that minimized the external diffusional limitations.