NDLI: Dynamic ruffling distortion of the heme substrate in non-canonical heme oxygenase enzymes

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Horak, Erik H. Liptak, Matthew D. Graves, Amanda B.
Description	Author Affiliation: Graves AB ( Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA. matthew.liptak@uvm.edu.); Horak EH ( Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA. matthew.liptak@uvm.edu.); Liptak MD ( Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA. matthew.liptak@uvm.edu.)
Abstract	Recent work by several groups has established that MhuD, IsdG, and IsdI are non-canonical heme oxygenases that induce significant out-of-plane ruffling distortions of their heme substrates enroute to mycobilin or staphylobilin formation. However, clear explanations for the observations of “nested” S = ½ VTVH MCD saturation magnetization curves at cryogenic temperatures, and exchange broadened $^{1}H$ NMR resonances at physiologically-relevant temperatures have remained elusive. Here, MCD and NMR data have been acquired for F23A and F23W MhuD–heme–CN, in addition to MCD data for IsdI–heme–CN, in order to complete assembly of a library of spectroscopic data for cyanide-inhibited ferric heme with a wide range of ruffling deformations. The spectroscopic data were used to evaluate a number of computational models for cyanide-inhibited ferric heme, which ultimately led to the development of an accurate NEVPT2/CASSCF model. The resulting model has a shallow, double-well potential along the porphyrin ruffling coordinate, which provides clear explanations for the unusual MCD and NMR data. The shallow, double-well potential also implies that MhuD-, IsdG-, and IsdI-bound heme is dynamic, and the functional implications of these dynamics are discussed.
ISSN	14779226
Issue Number	24
Journal	Dalton Trans.
Volume Number	45
e-ISSN	13645447
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2016-06-14
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Chemistry
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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