X-Ray Crystallography of Carbon Monoxide Dehydrogenases.
Carbon monoxide dehydrogenases (CODHs) are central players in the biogeochemical carbon monoxide (CO) cycle and have been extensively studied from the ecological level to the structural/molecular level. Of the two types of CODHs, the oxygen-tolerant CODHs use a bimetallic [CuSMo(=O)OH] center connected to the protein via a pyranopterin cofactor, whereas the oxygen-sensitive CODHs contain a [NiFe4S4-OHx]-cluster. Despite the fact that we have a basic understanding of how both types of CODHs use distinct active sites to catalyze the oxidation of CO with water to CO2, two protons, and two electrons (a reversible reaction in the cases of the oxygen-sensitive CODHs), many questions remain unanswered, especially concerning the electronic structures of the intermediate states. Since these states will likely be only revealed by the interplay of experimental and theoretical methods, there is a need to obtain accurate descriptions of the active site architectures in various states and, consequently, a need to generate crystals with good diffraction quality and collect data at element-specific wavelengths in order to determine the identity of elements in the case of mixed states. This chapter provides a description of the general working protocols for the crystallization and structural analysis of Cu,Mo-CODH and Ni,Fe-CODH that facilitates the mechanistic investigations of these important metalloenzymes.
['Jeoung|Jae-Hun|JH|', 'Martins|Berta M|BM|', 'Dobbek|Holger|H|']
D000445:Aldehyde Oxidoreductases D001665:Binding Sites D002248:Carbon Monoxide D020134:Catalytic Domain D018360:Crystallography, X-Ray D007501:Iron D008667:Metalloproteins D008958:Models, Molecular D008982:Molybdenum D009097:Multienzyme Complexes D009532:Nickel D014867:Water
Carbon monoxide dehydrogenase CODH Crystal dehydration Intermediate trapping Reaction intermediate Transient states