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 Front Cover indicates the effect that especially blue light exposure, but also ordinary laboratory or sunlight can have on the activity of PLP‐dependent enzymes. In their Full Paper, T. Gerlach et al. show that most of the PLP‐dependent enzymes tested showed a significant loss of activity upon illumination. Consequently, by carrying out the enzyme production and reaction in the dark, and in particular by preserving the cofactor PLP from illumination, the catalytic activity could be increased immensely, in one case up to tenfold. That the effect of light varies with the choice of PLP‐dependent enzyme was demonstrated by the fact that one enzyme was completely resistant to any type of illumination.More information can be found in the Full Paper by T. Gerlach et al.
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