Celebrating the 75th. Anniversary of the ACS of Puerto Rico 

University of Puerto Rico  

Mayagüez Campus  

Chemistry Department  

Departmental Seminar  

Celebrating the 75^th. Anniversary of the ACS of Puerto Rico       

by       

Ms. Jennifer Vargas Santiago 

UPRM PhD. Candidate  

Applied Chemistry and  Biophisics   

Friday, Dicember 9 th. , 2022 

10:30 am  

Link:  Reunión de Microsoft Teams  

¨Physiological effects of hydrogen sulfide (H2S) ¨

Abstract 

Extensive scientific data have shown that the physiological effects of hydrogen sulfide (H2S) depend on its concentrations in the body. However, the lack of an accurate method of quantification or biomarker has limited the discovery of the beneficial and detrimental quantities associated with various diseases. Research on the therapeutic use of H2S for various clinical applications is also limited by the fear of reaching dangerous thresholds of H2S concentrations in the body. This project provides the basis for developing different media in which H2S can be trapped and quantified in biological samples. Recombinant hemoglobin I (rHbI) from the clam Lucina pectinata has a high affinity for H2S, which makes it an attractive trapping medium. Therefore, rHbI was encapsulated in a silicon-based polymeric matrix and a three-dimensional collagen scaffold. Spectroscopic studies of rHbI encapsulated in tetramethyl orthosilicate (TMOS) demonstrate the ability of this hemeprotein chromophore to bind H2S. Fourier transform infrared (FTIR) and attenuated total reflection (ATR) spectroscopy analysis showed that the alpha helix is the predominant secondary structure, consistent with the values reported in the literature for the crystallographic structure of native HbI. These results revealed that encapsulation preserved the chromophore structure even in a crowded environment. Recombinant HbI immobilized in collagen also showed the ability to bind H2S by UV-Vis spectroscopy. Diffuse reflectance measurements transformed to Kubelka Munk units, analogous to UV-Vis, showed a linear correlation (R2=0.9987 and 0.9916) between absorption and concentrations of rHbI-H2O and rHbI-H2S, respectively, in a range of 1 to 35 μM. Therefore, the concentration of H2S can be determined by quantifying the rHbI-H2S complex, where one molecule of hemeprotein can bind only one molecule of H2S. The results suggest that rHbI can trap H2S without inducing structural changes. Our study provides insight into a novel method for immobilizing hemoproteins that can be used to develop an H2S biosensor using rHbI as a platform.