On CO egress from, and re-uptake by, the enzyme MauG, as a mimic of the acquisition of oxidizing agents by the pre-MADH_MauG system. A molecular mechanics approach.
In this work, by applying a non-deterministic, randomly-oriented minimal force to the dissociated CO ligand of the MauG-CO system, the molecular-dynamics (MD) behavior of this system could be quickly unraveled. It turned out that CO has no marked directional egress from the high-spin c-heme iron distal pocket. Rather, CO is able to exploit all interstices created during the protein fluctuations. Nonetheless, no steady route toward the surrounding solvent was ever observed: CO jumped first into other binding pockets before being able to escape the protein. In a few cases, on hitting the surrounding H(2)O molecules, CO was observed to reverse direction, re-entering the protein. A contention that conformational inversion of the P107 ring provides a gate to the iron ion is not supported by the present simulations.
Accademia Lucchese di Scienze, Lettere e Arti, Classe di Scienze, Palazzo Ducale, I-Lucca 55100, Italy. francesco.pietra@accademialucchese.it
Francesco
F
Pietra
D001665:Binding Sites; D002248:Carbon Monoxide / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006420:Hemeproteins / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D016877:Oxidants / Q000378:metabolism; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry* / Q000378:metabolism; D010231:Paracoccus denitrificans / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D011487:Protein Conformation
D006420:Hemeproteins; D016877:Oxidants; C031690:heme C; D006418:Heme; D002248:Carbon Monoxide; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors