Su Ma, Ph.D.
Current position: Postdoctoral Researcher
Project Funding: OXIDISE
Home University: BOKU
Duration of Stay: 6 months
Cellobiose dehydrogenase (CDH) is one of the few redox proteins that are capable of direct electron transfer (DET). To study DET in regard to CDH’s orientation on the gold electrode, cysteines were introduced to different surface areas of the DH by site-directed mutagenesis, resulting in seven variants with an surface exposed thiol group (from the introduced cysteine residue). A reaction between the free thiol group and maleimide groups pre-attached to the electrode surface was used to covalently bind the enzyme to the electrode surface. This led to anisotropically orientated CDH on the electrodes with a limited rotational freedom. The immobilization of CDH variants on the electrode surface was monitored by surface plasmon resonance (SPR) and cyclic voltammetry (CV) in absence or presence of the CDH substrate lactose was performed. DET and mediated electron transfer (MET) rates between the variants anisotropically orientated on gold electrodes and electrode surfaces will be determined and the optimal orientation elucidated. Further optimization of the enzyme immobilization will be based on the crystal structure of CDH, for which an efficient electron transfer is important for both biosensor and biofuel cell development.