Cinogy PlasmaDerm DBD

Plasma‐driven in situ production of hydrogen peroxide for biocatalysis

Peroxidases and peroxygenases are promising classes of enzymes for biocatalysis because of their ability to carry out one‐electron oxidation reactions and stereoselective oxyfunctionalizations. However, industrial application is limited, as the major drawback is the sensitivity toward the required peroxide substrates. Herein, we report a novel biocatalysis approach to circumvent this shortcoming: in situ production of H2O2 by dielectric barrier discharge plasma. The discharge plasma can be controlled to produce hydrogen peroxide at desired rates, yielding desired concentrations. Using horseradish peroxidase, it is demonstrated that hydrogen peroxide produced by plasma treatment can drive the enzymatic oxidation of model substrates. Fungal peroxygenase is then employed to convert ethylbenzene to (R)‐1‐phenylethanol with an ee of >96 % using plasma‐generated hydrogen peroxide. As direct treatment of the reaction solution with plasma results in reduced enzyme activity, the use of plasma‐treated liquid and protection strategies are investigated to increase total turnover. Technical plasmas present a noninvasive means to drive peroxide‐based biotransformations.

Publisher: 
Applied Microbiology
Project: 
SFB 1316
Authors: 
A. Yayci
A. Gomez Baraibar
M. Krewig
E. Fernandez Fueyo
F. Hollmann
M. Alcaide
R. Kourist
J. Bandow

Dielectric barrier discharge plasma treatment affects stability, metal ion coordination, and enzyme activity of bacterial superoxide dismutases

A molecular‐level understanding of the effects of atmospheric‐pressure plasma on biological samples requires knowledge of the effects on proteins. Superoxide dismutases, which detoxify superoxide under oxidative stress conditions, play a key role in bacterial plasma resistance. Investigation of the impact of dielectric barrier discharge (DBD) treatment on purified superoxide dismutases SodA and SodB of Escherichia coli showed that DBD treatment caused a rapid protein degradation, with only 8% of protein remaining after 10 min. The affinity of SodA for the metal cofactor Mn2+ was reduced. Mass spectrometry, in conjunction with coupled‐cluster calculations, revealed that modifications of amino acid residues in the active site can explain the decreased metal affinity and a distortion of the coordination geometry responsible for the activity loss.

Publisher: 
Applied Microbiology
Project: 
SFB 1316
Authors: 
M. Krewig
C. Jung
E. Dobbelstein
B. Schubert
T. Jacob
J. Bandow