Circular Permutated PQQ‐Glucose Dehydrogenase as an Ultrasensitive Electrochemical Biosensor

Protein biosensors play an increasingly important role as reporters for research and clinical applications. Here we present approach the construction of fully integrated but modular electrochemical based on principal component glucose monitors PQQ-glucose dehydrogenase (PQQ-GDH). We designed allosterically regulated circular permutated variants PQQ-GDH that show large (>10-fold) changes in enzymatic activity following intramolecular scaffolding newly generated N- C termini by ligand binding domain/ligand complexes. The developed demonstrated sub-nanomolar affinities small molecules proteins colorimetric assays. For instance, concentration Cyclosporine A could be measured 1 μL undiluted blood with same accuracy leading diagnostic technique uses 50 times more sample. further used this biosensor to construct highly porous gold bioelectrodes capable robustly detecting concentrations low 20 pM retained functionality samples containing at least 60 % human serum.