Optimising Electrical Interfacing between the Trimeric Copper Nitrite Reductase and Carbon Nanotubes.

The immobilization of copper-containing nitrite reductase (NiR) from Alcaligenes faecalis on functionalised multi-walled carbon nanotube (MWCNT) electrodes is reported. It is demonstrated that this immobilization is mainly driven by hydrophobic interactions, promoted by the modification of MWCNTs with adamantyl groups. Direct electrochemistry shows high bioelectrochemical reduction of nitrite at the redox potential of NiR with high current density of 1.41 mA cm-2 . Furthermore, the desymmetrization of the trimer upon immobilization induces an independent electrocatalytic behavior for each of the three enzyme subunits, corroborated by an electron-tunneling distance dependence.

Bioinformatic Analysis of Immobilized Enzymes: Towards a Better Understanding of The Guiding Forces.

Protein bioinformatics has been applied to a myriad of opportunities in biocatalysis from enzyme engineering to enzyme discovery, but its application in enzyme immobilization is still very limited. Enzyme immobilization brings clear advantages in terms of sustainability and cost-efficiency but is still limited in its implementation. This, because it is a technique that remains tied to a quasi-blind protocol of trial and error, and therefore, is regarded as a time-intensive and costly approach. Here, we present the use of a set of bioinformatic tools to rationalize the results of protein immobilization that have been previously described. The study of proteins with these new tools allows the discovery of key driving forces in the process of immobilization that explain the obtained results, moving us a step closer to the final goal: predictive enzyme immobilization protocols.

Minimalistic peptidic scaffolds harbouring an artificial carbene-containing amino acid modulate reductase activity.

Inspired by the boom of new artificial metalloenzymes, we developed an Fmoc-protected histidinium salt (Hum) as N-heterocyclic carbene precursor. Hum was placed via solid-phase peptide synthesis into short 7-mer peptides. Upon iridation, the metallo-peptidic construct displayed activity in catalytic hydrogenation that outperforms small molecule analogues and which is dependent on the peptide sequence, a typical feature of metalloenzymes.