Deactivation of Formate Dehydrogenase (FDH) in Solution and at Gas‐Liquid Interfaces

Abstract

Enzymes, increasingly important in the synthesis of fine chemicals and pharmaceutical intermediates, are often insufficiently stable under reacting conditions. We have investigated the stability, in homogeneous aqueous solution and at gas-liquid interfaces, of formate dehydrogenase (FDH), important for cofactor regeneration, from Candida boidinii and overexpressed in E. coli. When exposed to mechanical stress, residual activity, [E](t)/[E](0), and residual protein were found to scale proportionally with gas-liquid surface area in the bubble column, verifying a surface-driven process, and with time and total throughput in a gear pump, but did not seem to be influenced much by shear in a Couette viscometer. All FDH variants are deactivated by chaotropes but not kosmotropes: the first-order deactivation constant k(d) correlates well with the Jones-Dole coefficient B but not well with the surface tension increment deltasigma of various concentrated ammonium salt solutions. This finding might provide guidance for focusing the search for quantitative theories of Hofmeister effects.

Stability of Protein Pharmaceuticals: An Update

“…However, recent studies have begun to examine these effects. Enzyme deactivation in aqueous solution and at the gaswater interface in a bubble cell was found to depend on both bubble surface area size and salt concentration, with higher molarity of ammonium formate leading to increased deactivation (369). Salt-specific effects were investigated, and the enzyme was deactivated by chaotropes but not kosmotropes, providing some guidance regarding possible quantitative mechanisms of Hofmeister effects.…”

Oxygen transfer rates and requirements in oxidative biocatalysis

“…Because enzymes can be inactivated by gas/liquid interfaces (Bommarius & Karau, 2005), bubble-less aeration through membranes may improve the operational stability of the enzyme. Figure 2 shows the estimated specific membrane areas necessary in order to reach given productivities using different forms of the biocatalyst.…”

Effects of the kinematic viscosity and surface tension on the bubble take-off period in a catalase–hydrogen peroxide system

“…As a result, both values slightly increased (1.02 and 1.10 times larger, respectively). Experimentally, after the addition of glucose oxidase, bubbles did not seem to form easily for an unknown reason [21][22][23]. We therefore prepared a cell with a longer tunnel (cell wall thickness 4.0 mm) and a small "tooth" at the end of it ( Fig.…”