Reverse Spin‐Crossover and High‐Pressure Kinetics of the Heme Iron Center Relevant for the Operation of Heme Proteins under Deep‐Sea Conditions

Abstract

By design of a heme model complex with a binding pocket of appropriate size and flexibility, and by elucidating its kinetics and thermodynamics under elevated pressures, some of the pressure effects are demonstrated relevant for operation of heme‐proteins under deep‐sea conditions. Opposite from classical paradigms of the spin‐crossover and reaction kinetics, a pressure increase can cause deceleration of the small‐molecule binding to the vacant coordination site of the heme‐center in a confined space and stabilize a high‐spin state of its Fe center. This reverse high‐pressure behavior can be achieved only if the volume changes related to the conformational transformation of the cavity can offset the volume changes caused by the substrate binding. It is speculated that based on these criteria nature could make a selection of structures of heme pockets that assist in reducing metabolic activity and enzymatic side reactions under extreme pressure conditions.

Heme: From quantum spin crossover to oxygen manager of life

“…Wyman, and Changeux in 1965 [166], and this cooperativity has since been a highly researched topic [163] Ivanovíc-Burmazovic and co-workers recently used three synthetic models with variable access to the distal coordination site of heme: Accordingly, proteins and artificial scaffolds can be tuned to control ligand binding kinetics so that high-pressure effects, which would normally favor the compact bound state and retard dissociation rates, can be balanced or even reversed [170]. This may be a necessary tuning strategy of heme proteins at high pressure, e.g.…”

A Facile Synthesis of Green‐Blue Carbon Dots from Artocarpus lakoocha Seeds and Their Application for the Detection of Iron (III) in Biological Fluids and Cellular Imaging

“…The insufficiency of iron causes many health problems in the human being like anemia, loss of appetite, frequent fatigue, reduced work routine and decreased immunity. Whereas overload accumulation of iron in blood encourages a variety of biological disorders such as fibrosis, tissue damage of different organs and production of reactive oxygen species which results in deterioration of proteins, nucleic acids and lipids . Hence, for better human health, observation of concentrations of iron in biological fluids is imperative .…”