Author(s)

Jennifer Vargas-Santiago, Juan López-Garriga^*

Department of Chemistry, University of Puerto Rico, Mayaguez, Puerto Rico.

Hydrogen sulfide (H₂S) has been related to be toxic and to have a role in human physiological functions. Therefore, there is a necessity to comprehend ways to scavenger hydrogen sulfide from different media. Here, we used recombinant metaquo-Hemoglobin I (metHbI) from Lucina pectinata and metaquo-myoglobin (metMb) encapsulated in the tetramethyl orthosilicate gel (TMOS), to facilitate the understanding of H₂S transfer toward these metaquo-hemeproteins. In this sol-gel environment, metHbI binds and releases H₂S with rate constants of 0.0597 M^-1·s^-1 and 6.67 × 10^-5 s^-1, respectively. The process generates an H₂S affinity constant (k_on/k_off) of 8.9 × 10² M^-1, which is 10⁷ lowers than the analogous constant in solution (6.3 × 10⁹ M^-1). Although the H₂S k_off for the rHbI-H₂S complex is almost similar with both sol-gel and solution. To further understand how the H₂S k_off from rHbI-H₂S in solution (5 μM) is influenced by the protein concentration gradient, metHbI and metMb (25 μM) encapsulated in TMOS sol-gel. Under these circumstances, the H₂S transfer from a solution of the rHbI-H₂S complex to encapsulated hemeprotein resulted in k_off values of 1.90 × 10^-4 s^-1, and 2.09 × 10^-4 s^-1 leading to the formation of rHbI-H₂S and Mb-H₂S species, respectively. The results suggest that the: 1) extreme ionic TMOS construct limits the H₂S pathways to reach the hemeprotein active center, 2) possible interaction with metHbI hydrophilic forces increases the hydrogen bonding networking and decreases the H₂S association constant, 3) hemeproteins concentration gradients between solution and sol-gels also influence its hydrogen sulfide transfer. In the presence of oxygen or hydrogen peroxide metMb generated a mixture of Mb-H₂S and sulfmyoglobin derivative, while encapsulated metHbI reaction did not produce the sulfheme species. Consequently, the results show that metHbI encapsulated in TMOS is an excellent trap for H₂S from solution or gas media.

Hydrogen sulfide, Lucina pectinata, Inorganic Polymer, Biomedical Applications, Protein Immobilization

Vargas-Santiago, J. and López-Garriga, J. (2019) Transfer and Reactivity of Hydrogen Sulfide with Immobilized Hemeproteins in Polymeric Matrix. Journal of Encapsulation and Adsorption Sciences, 9, 109-126. doi: 10.4236/jeas.2019.92006.