Structural highlights
FunctionPHFL_NITV2 May be involved in hydrogen uptake for the reduction of sulfate to hydrogen sulfide in an electron transport chain. Cytochrome c3 is likely to be the physiological electron carrier for the enzyme. Publication Abstract from PubMedThe noncanonical amino acid, para-cyanophenylalanine (CNF), when incorporated into metalloproteins, functions as an infrared spectroscopic probe for the redox state of iron-sulfur clusters, offering a strategy for determining electron occupancy in the electron transport chains of complex metalloenzymes. A redshift of approximately 1-2 cm(-1) in the nitrile (NC) stretching frequency is observed, following reduction of spinach ferredoxin modified to contain CNF close to its [2Fe-2S] center, and this shift is reversed on re-oxidation. We extend this to CNF positioned near to the proximal [4Fe-4S] cluster of the [FeFe] hydrogenase from Desulfovibrio desulfuricans. In combination with a distal [4Fe-4S] cluster and the [4Fe-4S] cluster of the active site 'H-cluster' ([4Fe-4S](H)), the proximal cluster forms an electron relay connecting the active site to the surface of the protein. Again, a reversible shift in wavenumber for CNF is observed, following cluster reduction in either apo-protein (containing the iron-sulfur clusters but lacking the active site) or holo-protein with intact active site, demonstrating the general applicability of this approach to studying complex metalloenzymes. Cyanophenylalanine as an Infrared Probe for Iron-Sulfur Cluster Redox State in Multicenter Metalloenzymes.,Duan Z, Wei J, Carr SB, Ramirez M, Evans RM, Ash PA, Rodriguez-Macia P, Sachdeva A, Vincent KA Chembiochem. 2025 May 10:e2500251. doi: 10.1002/cbic.202500251. PMID:40347495[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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