Modeling the hydrogen sulfide binding to heme.

Modeling the hydrogen sulfide binding to heme.
J Inorg Biochem. 2018 Apr 21;184:108-114
Authors: Ostojić BD, Schwerdtfeger P, Đorđević DS
Abstract
The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the H2S addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-H2S aduct is bound by 13.7 kcal/mol at the CCSD(T) level of theory. Relaxed potential energy curves for the lowest lying spin states of the H2S to FeP(Im) binding using DFT reveal that the binding process is associated with a "double spin-crossover" reaction with the existence of long-distance van der Waals minima only 5-7 kcal/mol above the FeP(Im)-H2S ground state. The fact that the energy of the singlet ground state of FeP(Im)-H2S is so close in energy to the dissociation products FeP(Im) + H2S points towards the reversibility of the H2S adsorption/desorption process in biochemical reactions.
PMID: 29705379 [PubMed - as supplied by publisher]

Source: Journal of Inorganic Biochemistry - April 21, 2018 Category: Biochemistry Authors: Ostojić BD, Schwerdtfeger P, Đorđević DS Tags: J Inorg Biochem Source Type: research