Sulfmyoglobin conformational change: A role in the decrease of oxy-myoglobin functionality

Abstract

This work is focused at understanding the interaction of H2S with Myoglobin (Mb), in particular the Sulfmyoglobin (SMb) product, whose physiological role is controversial and not well understood. The scattering curves, Guinier, Kratky, Porod and P(r) plots were analyzed for oxy-Mb and oxy-Hemoglobin I (oxyHbI) in the absence and presence of H2S, using Small and Wide Angle X-ray Scattering (SAXS/WAXS) technique. Three dimensional models were also generated from the SAXS/WAXS data. The results show that SMb formation, produced by oxyMb and H2S interaction, induces a change in the protein conformation where its envelope has a very small cleft and the protein is more flexible, less rigid and compact. Based on the direct relationship between Mb's structural conformation and its functionality, we suggest that the conformational change observed upon SMb formation plays a contribution to the protein decrease in O2 affinity and, therefore, on its functionality.

Characterization of Recombinant His-Tag Protein Immobilized onto Functionalized Gold Nanoparticles

“…These wavenumbers of amide I and amide II agree with the typical values for proteins with primarily α-helical structures [28], consistent with the crystallographic structure of the native HbI protein [34]. Previous analyses of small/wide angle X-ray scattering (SWAXS) show that the native HbI protein is similar in global three-dimensional structure to the (His) 6 -rHbI protein [19,23]. In addition, before the adsorption of the protein, the spectrum of the Au/AuNPs/3MPA/Ni 2+ electrode (Figure 3, red line) did not show the characteristic IR bands of proteins in the amide regions.…”

“…According to the experimental data in the RSCB Protein Data Bank (PDB id:1B0B), a unit cell of native HbI is 4.944 nm × 3.795 nm × 4.137 nm, which is very similar to our protein thickness results when the thickness of the previous steps is subtracted (~4.7 nm). As mentioned previously, according to SWAXS results published before [19,23], the native HbI protein is similar, in global three-dimensional structure to the (His) 6 -rHbI protein. Furthermore, the SWAXS analysis reported a radius of gyration (Rg) between 1.8–1.9 nm for (His) 6 -rHbI, which corresponds to an average diameter of 3.7 nm.…”

“…The hemoglobin I (HbI), from the clam Lucina pectinata has a unique sequence of amino acids in the active center which are thought to be responsible for the unusually high affinity for hydrogen sulfide (H 2 S) [16,17,18,19,20]. Due to this high affinity for H 2 S, HbI has been proposed as a biocomponent for an H 2 S-biosensor [11,21] and to study H 2 S-protein interactions [19,22]. The native HbI has been cloned with an hexahistidine tag [20] and was recently fused with an hexalysine tag [23].…”

Meat color and iridescence: Origin, analysis, and approaches to modulation

“…The meat color is stable until the amount of metmyoglobin predominates and undesirable color variations become visible, in particular color changes to the typical gray‐brown caused by metmyoglobin. When oxidation of myoglobin occurs in the presence of sulfhydryl groups and oxygen, sulfmyoglobin—a green pigment—is formed (Figure ) (Nicol et al., 1970; Román‐Morales et al., 2016). The conversion to sulfmyoglobin can be indicated by the typical absorption bands at 620 or 715 nm showing the formation of a sulfur ring (Román‐Morales et al., 2016).…”

Interactions of reactive sulfur species with metalloproteins

“…However, like Hb, Mb was also shown to form the sulfheme-containing derivative sulfmyoglobin (sulfMb) in vitro . As sulfMb has three orders of magnitude lower affinity to oxygen than Mb, its endogenous formation may cause hypoxic conditions in muscle tissues [ 99 , 154 ].…”