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Title: Coupling of helix E-F motion with the O-nitrito and 2-nitrovinyl coordination in myoglobin
Authors: Ioannou, Androulla 
Lambrou, Alexandra 
Daskalakis, Evangelos 
Pinakoulaki, Eftychia 
Keywords: Heme proteins;Molecular Dynamics;Nitrite;Raman spectroscopy
Category: Agricultural Biotechnology
Field: Agricultural Sciences
Issue Date: 1-Feb-2017
Publisher: Elsevier B.V.
Source: Biophysical Chemistry Volume 221, 1 February 2017, Pages 10-16
Abstract: Myoglobin (Mb) is known to react slowly with nitirite to form the green pigment by NO2− cordination to the heme Fe in the O-binding nitrito (O1[sbnd]N[dbnd]O2) mode and to the heme 2-vinyl position. Nitrite is a powerful oxidizing agent and a biological reservoir for NO that has been implicated in a variety of aerobic biological systems. Accordingly, it is important to elucidate the nature and variety of NO2− reaction mechanisms with Mb. We have performed principal component analysis (PCA, or essential dynamics) on Molecular Dynamics trajectories of all Mb[sbnd]NO2 coordination states to resolve the most important motions in the protein at 298 K. We show that the coordination or removal of NO2− to/from the heme iron is associated mainly with a motion of helix E and the coordination of NO2− to the 2-vinyl is associated with a motion of helix F and a correlated motion of helices E-F. This latter correlated motion can be attributed to the interaction of Val68 and Ile107 with the 2-nitrovinyl moiety. The resonance Raman results show that coordination of NO2− to the 2-vinyl is increased at pH 6.0 demonstrating that the amide protons in the F helix are not protected from access of solvent water and the helix F motion allows solvent access to the 2-vinyl group, without affecting the coordination to the heme Fe.
ISSN: 03014622
DOI: 10.1016/j.bpc.2016.11.009
Rights: © 2016 Elsevier B.V.
Type: Article
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