| Summary: | 碩士 === 國立中正大學 === 化學工程所 === 93 === Because the public concern for the possible transmission of HIV or hepatitis virus via blood transfusion, the oxygen-carrying blood substitutes have been extensively studied and developed. Among various blood substitutes, hemoglobin-based blood substitutes are most promising. There are two protein structures of hemoglobin, R and T states. Hemoglobin has greater affinity for oxygen in R state than in T state. Inside the red blood cells (RBCs), 2,3-diphosphoglycerate (2,3-DPG) gifted with five negative charges binds to hemoglobin, stabilizing hemoglobin in T state and helping oxygen release from hemoglobin for the rest of tissues. Our goal is to crosslink hemoglobin with the 2,3-DPG-like molecule for better oxygen release. Glutathione (GSH) consisted of three amino acids presents in a substantial amount in cells, serving as an anitoxidant. In physiological condition, the net charge of glutathione is positive one, two negative charges from carboxylic groups and one positive charge from amino group. If we eliminate the positive charge in the amino group by acetylation, we can make acetylated GSH carries two negative charges, which may become a good oxygen modulator for hemoglobin. In this study, acetyl-GSH was crosslinked to the outer structure of hemoglobin through Maleimide— polyethyleneglycol—N-hydroxysuccinimidyl (MAL-PEG-NHS). MAL was the functional group to crosslink PEG with cysteine in GSH, whereas NHS is to crosslink PEG with lysines in hemoglobin. Our results show that the oxygen dissociation curve of hemoglobin crosslinked with acetyl-GSH-PEG shifts to the right as compared to the control. Although the reactivities with nitric oxide are similar between hemoglobin and acetyl-GSH-PEG-hemoglobin, the greater viscosity and particle size of PEG modified hemoglobin will exhibit a better blood vessel response due to the increase of endothelial nitric oxide release and the avoidance of extravascalation of hemoglobin.
|
|---|
