Title

A Parallel Architecture For Interactively Rendering Scattering And Refraction Effects

Abstract

MauG is a diheme enzyme possessing a five-coordinate high-spin heme with an axial His ligand and a six-coordinate low-spin heme with His-Tyr axial ligation. A Ca 2+ ion is linked to the two hemes via hydrogen bond networks, and the enzyme activity depends on its presence. Removal of Ca 2+ altered the electron paramagnetic resonance (EPR) signals of each ferric heme such that the intensity of the high-spin heme was decreased and the low-spin heme was significantly broadened. Addition of Ca 2+ back to the sample restored the original EPR signals and enzyme activity. The molecular basis for this Ca 2+-dependent behavior was studied by magnetic resonance and Mössbauer spectroscopy. The results show that in the Ca 2+-depleted MauG the high-spin heme was converted to a low-spin heme and the original low-spin heme exhibited a change in the relative orientations of its two axial ligands. The properties of these two hemes are each different than those of the heme in native MauG and are now similar to each other. The EPR spectrum of Ca 2+-free MauG appears to describe one set of low-spin ferric heme signals with a large g max and g anisotropy and a greatly altered spin relaxation property. Both EPR and Mössbauer spectroscopic results show that the two hemes are present as unusual highly rhombic low-spin hemes in Ca 2+-depleted MauG, with a smaller orientation angle between the two axial ligand planes. These findings provide insight into the correlation of enzyme activity with the orientation of axial heme ligands and describe a role for the calcium ion in maintaining this structural orientation that is required for activity. © 2012 American Chemical Society.

Publication Date

2-29-2012

Publication Title

IEEE Computer Graphics and Applications

Volume

32

Issue

8

Number of Pages

34-43

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1109/MCG.2011.106

Socpus ID

84857392661 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84857392661

This document is currently not available here.

Share

COinS