Related Experiment Video
Updated: Mar 12, 2026

Measurement of Heme Synthesis Levels in Mammalian Cells
Published on: July 9, 2015
HNO-Binding in Heme Proteins: Effects of Iron Oxidation State, Axial Ligand, and Protein Environment
Rahul L Khade1, Yuwei Yang1, Yelu Shi1
1Department of Biomedical Engineering, Chemistry and Biological Sciences, Stevens Institute of Technology, 1 Castle Point on Hudson, Hoboken, NJ, 07030, USA.
Abstract:
HNO plays significant roles in many biological processes. Numerous heme proteins bind HNO, an important step for its biological functions. A systematic computational study was performed to provide the first detailed trends and origins of the effects of iron oxidation state, axial ligand, and protein environment on HNO binding. The results show that HNO binds much weaker with ferric porphyrins than corresponding ferrous systems, offering strong thermodynamic driving force for experimentally observed reductive nitrosylation. The axial ligand was found to influence HNO binding through its trans effect and charge donation effect. The protein environment significantly affects the HNO hydrogen bonding structures and properties. The predicted NMR and vibrational data are in excellent agreement with experiment. This broad range of results shall facilitate studies of HNO binding in many heme proteins, models, and related metalloproteins.
Related Concept Videos
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Protein and Protein Structure
A protein's shape is critical to its function. For example, an enzyme...
Cooperative Allosteric Transitions
Hemoglobin
When all four heme groups are bound to oxygen, the resulting molecule is called oxyhemoglobin. As a result, arterial blood...
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
Protein Denaturation

