Beschreibung:
Per‐ and polyfluoroalkyl substances (PFAS) are ubiquitous pollutants found in water and land environments. Environmental buildup of organohalides, such as perchloroethylene (PCE) and trichloroethene (TCE), used in dry cleaning, firefighting foams, and food packaging, pose an increasing public health risk due to their slow degradation. PFAS molecules are now observed in the blood of humans and animals across the world, and their full impact on health is yet to be determined. Studies of PFAS biodegradation have been reported within various microbial organisms. One reductive dehalogenase identified is PceA from Sulfurospirillium multivorans. The Summit Country Day School MSOE Center for Biomolecular Modeling MAPS team used 3D modeling and printing technology to investigate the active site of the reductive dehalogenase PceA. PceA is a homodimer with two independent active sites. Each active site contains a norpseudo‐B12, two 4Fe‐4S clusters as well as three highly conserved amino acids, Tyr246, Arg305, and Asn272. The short distances between the proximal iron‐sulfur cluster and the cobalt ion bound to the corrin ring of norpseudo‐B12 are thought to allow rapid electron transfer for catalysis. The invariant Tyr246 can donate a proton to neutralize the carbanion formed during catalysis. Deprotonated Tyr246 may be stabilized by the guanidinium side chain of Arg305. Additionally, the active sites have a hydrophobic pocket lined with bulky nonpolar amino acids Phe38, Trp56, Tyr102, Trp96, Tyr382 and Trp376. The tightly packed hydrophobic sidechains provide a gate for substrate selection. Understanding PFAS biodegradation and identifying additional reductive dehalogenases is urgent in addressing the pollution that faces our environment and critical in ensuring the health of humans and ecosystems.