Infrared spectroscopy reveals metal-independent carbonic anhydrase activity in crotonyl-CoA carboxylase/reductase.

The conversion of CO by enzymes such as carbonic anhydrase or carboxylases plays a crucial role in many biological processes. However, methods following the microscopic details of CO conversion at the active site are limited. Here, we used infrared spectroscopy to study the interaction of CO, water, bicarbonate, and other reactants with β-carbonic anhydrase from (CA) and crotonyl-CoA carboxylase/reductase from (Ccr), two of the fastest CO-converting enzymes in nature.

Conformational Dynamics of the Most Efficient Carboxylase Contributes to Efficient CO Fixation.

Crotonyl-CoA carboxylase/reductase (Ccr) is one of the fastest CO fixing enzymes and has become part of efficient artificial CO-fixation pathways in vitro, paving the way for future applications. The underlying mechanism of its efficiency, however, is not yet completely understood. X-ray structures of different intermediates in the catalytic cycle reveal tetramers in a dimer of dimers configuration with two open and two closed active sites.

Intersubunit Coupling Enables Fast CO-Fixation by Reductive Carboxylases.

Enoyl-CoA carboxylases/reductases (ECRs) are some of the most efficient CO-fixing enzymes described to date. However, the molecular mechanisms underlying the extraordinary catalytic activity of ECRs on the level of the protein assembly remain elusive. Here we used a combination of ambient-temperature X-ray free electron laser (XFEL) and cryogenic synchrotron experiments to study the structural organization of the ECR from .

Conformational sampling and polarization of Asp26 in pK calculations of thioredoxin.

Thioredoxin is a protein that has been used as model system by various computational methods to predict the pK of aspartate residue Asp26 which is 3.5 units higher than a solvent exposed one (eg, Asp20). Here, we use extensive atomistic molecular dynamics simulations of two different protonation states of Asp26 in combination with conformational analysis based on RMSD clustering and principle component analysis to identify representative conformations of the protein in solution.