The Effect of Visible Light on the Catalytic Activity of PLP‐Dependent Enzymes

Abstract

Pyridoxal 5'-phosphate (PLP)-dependent enzymes are a versatile class of biocatalysts and feature a variety of industrial applications. However, PLP is light sensitive and can cause inactivation of enzymes in certain light conditions. As most of the PLP-dependent enzymes are usually not handled in dark conditions, we evaluated the effect of visible light on the activity of PLP-dependent enzymes during production as well as transformation. We tested four amine transaminases, from Chromobacterium violaceum, Bacillus megaterium, Vibrio fluvialis and a variant from Arthrobacter species as well as two lysine decarboxylases, from Selenomonas ruminantium and the LDCc from Escherichia coli. It appeared that five of these six enzymes suffered from a significant decrease in activity by up to 90 % when handled in laboratory light conditions. Surprisingly, only the amine transaminase variant from Arthrobacter species appeared to be unaffected by light exposure and even showed an activation to 150 % relative activity over the course of 6 h regardless of the light conditions.

The Role of Buffer, Pyridoxal 5’‐Phosphate and Light on the Stability of the Silicibacter Pomeroyi Transaminase

“…The effect of light on transaminase‐catalysed reactions was explored by Gerlach et al [26] . Depending on the transaminase employed and buffer, light was an important factor for the change in enzyme activity and significant differences between light and dark samples could be observed.…”

“…The effect of light on transaminase-catalysed reactions was explored by Gerlach et al [26] Depending on the transaminase employed and buffer, light was an important factor for the change in enzyme activity and significant differences between light and dark samples could be observed. Because the impact of light varied largely from enzyme to enzyme and no prediction could be made, we investigated the impact of light on SpATA.…”

“…Furthermore, a destruction of histidine and cysteine residues was observed, which was ascribed to be caused by the PLP‐mediated photooxidation [25] . Further research showed the inactivating effect of light on different PLP‐dependent enzymes, yet no clear explanation has since been found connecting the differences between different buffers and enzyme, as the effect varies significantly [26] …”

“…[25] Further research showed the inactivating effect of light on different PLP-dependent enzymes, yet no clear explanation has since been found connecting the differences between different buffers and enzyme, as the effect varies significantly. [26] In this work we investigate the effect of two different buffers, different PLP-concentrations, and light on the stability of the Silicibacter pomeroyi transaminase and report possible explanations for the large impact of these parameters.…”

Modulation of Transaminase Activity by Encapsulation in Temperature‐Sensitive Poly(N‐acryloyl glycinamide) Hydrogels

“…For future experiments a small increase in reusability for both, immobilized and free Bm TA, might be achieved by running all reactions in the dark: A recent study published by our group showed a 10–20 % decrease of Bm TA activity upon blue light exposure, and also some activity loss upon laboratory light exposure. [24b] …”